Monthly Archives: September 2021

How contagious is Delta? How long are you infectious? Is it more deadly? A quick guide to the latest science

How contagious is Delta? How long are you infectious? Is it more deadly? A quick guide to the latest science

September 29, 2021 6.13am AEST


  1. Lara Herrero Research Leader in Virology and Infectious Disease, Griffith University

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Lara Herrero does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.


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Delta was recognised as a SARS-CoV-2 variant of concern in May 2021 and has proved extremely difficult to control in unvaccinated populations.

Delta has managed to out-compete other variants, including Alpha. Variants are classified as “of concern” because they’re either more contagious than the original, cause more hospitalisations and deaths, or are better at evading vaccines and therapies. Or all of the above.

So how does Delta fare on these measures? And what have we learnt since Delta was first listed as a variant of concern?

Read more: Is Delta defeating us? Here’s why the variant makes contact tracing so much harder

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How contagious is Delta?

The R0 tells us how many other people, on average, one infected person will pass the virus on to.

Delta has an R0 of 5-8, meaning one infected person passes it onto five to eight others, on average.

This compares with an R0 of 1.5-3 for the original strain.

So Delta is twice to five times as contagious as the virus that circulated in 2020.

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What happens when you’re exposed to Delta?

SARS-CoV-2 is the virus that causes COVID-19. SARS-CoV-2 is transmitted through droplets an infected person releases when they breathe, cough or sneeze.

In some circumstances, transmission also occurs when a person touches a contaminated object, then touches their face.

Four Turkish men walk across an open town space.
One person infected with Delta infects, on average, five to eight others. Shutterstock

Once SARS-CoV-2 enters your body – usually through your nose or mouth – it starts to replicate.

The period from exposure to the virus being detectable by a PCR test is called the latent period. For Delta, one study suggests this is an average of four days (with a range of three to five days).

That’s two days faster than the original strain, which took roughly six days (with a range of five to eight days).

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The virus then continues to replicate. Although often there are no symptoms yet, the person has become infectious.

People with COVID-19 appear to be most infectious two days before to three days after symptoms start, though it’s unclear whether this differs with Delta.

The time from virus exposure to symptoms is called the incubation period. But there is often a gap between when a person becomes infectious to others to when they show symptoms.

As the virus replicates, the viral load increases. For Delta, the viral load is up to roughly 1,200 times higher than the original strain.

With faster replication and higher viral loads it is easy to see why Delta is challenging contact tracers and spreading so rapidly.

What are the possible complications?

Like the original strain, the Delta variant can affect many of the body’s organs including the lungs, heart and kidneys.

Complications include blood clots, which at their most severe can result in strokes or heart attacks.

Around 10-30% of people with COVID-19 will experience prolonged symptoms, known as long COVID, which can last for months and cause significant impairment, including in people who were previously well.

Woman in a mask waits in hospital waiting room.
Even previously well people can get long COVID. Shutterstock

Longer-lasting symptoms can include fatigue, shortness of breath, chest pain, heart palpitations, headaches, brain fog, muscle aches, sleep disturbance, depression and the loss of smell and taste.

Is it more deadly?

Evidence the Delta variant makes people sicker than the original virus is growing.

Preliminary studies from Canada and Singapore found people infected with Delta were more likely to require hospitalisation and were at greater risk of dying than those with the original virus.

In the Canadian study, Delta resulted in a 6.1% chance of hospitalisation and a 1.6% chance of ICU admission. This compared with other variants of concern which landed 5.4% of people in hospital and 1.2% in intensive care.

In the Singapore study, patients with Delta had a 49% chance of developing pneumonia and a 28% chance of needing extra oxygen. This compared with a 38% chance of developing pneumonia and 11% needing oxygen with the original strain.

Similarly, a published study from Scotland found Delta doubled the risk of hospitalisation compared to the Alpha variant.

Older man with cold symptoms lays down, wrapped in a blanket, cradling his head, holding a tissue to his nose.
Emerging evidence suggests Delta is more likely to cause severe disease than the original strain. Shutterstock

How do the vaccines stack up against Delta?

So far, the data show a complete course of the Pfizer, AstraZeneca or Moderna vaccine reduces your chance of severe disease (requiring hospitalisation) by more than 85%.

While protection is lower for Delta than the original strain, studies show good coverage for all vaccines after two doses.

Can you still get COVID after being vaccinated?

Yes. Breakthrough infection occurs when a vaccinated person tests positive for SARS-Cov-2, regardless of whether they have symptoms.

Breakthrough infection appears more common with Delta than the original strains.

Most symptoms of breakthrough infection are mild and don’t last as long.

It’s also possible to get COVID twice, though this isn’t common.

How likely are you to die from COVID-19?

In Australia, over the life of the pandemic, 1.4% of people with COVID-19 have died from it, compared with 1.6% in the United States and 1.8% in the United Kingdom.

Data from the United States shows people who were vaccinated were ten times less likely than those who weren’t to die from the virus.

The Delta variant is currently proving to be a challenge to control on a global scale, but with full vaccination and maintaining our social distancing practices, we reduce the spread.

Mind diet linked to better cognitive performance

Mind diet linked to better cognitive performance

MedicalXpress Breaking News-and-Events|September 22, 2021

Aging takes a toll on the body and on the mind. For example, the tissue of aging human brains sometimes develops abnormal clumps of proteins that are the hallmark of Alzheimer’s disease. How can you protect your brain from these effects?

Researchers at Rush University Medical Center have found that older adults may benefit from a specific diet called the MIND diet even when they develop these protein deposits, known as amyloid plaques and tangles. Plaques and tangles are a pathology found in the brain that build up in between nerve cells and typically interfere with thinking and problem-solving skills.

Developed by the late Martha Clare Morris, ScD, who was a Rush nutritional epidemiologist, and her colleagues, the MIND diet is a hybrid of the Mediterranean and DASH (Dietary Approaches to Stop Hypertension) diets. Previous research studies have found that the MIND diet may reduce a person’s risk of developing Alzheimer’s disease dementia.

Now a study has shown that participants in the study who followed the MIND diet moderately later in life did not have cognition problems, according to a paper published on Sept. 14 in the Journal of Alzheimer’s Disease.

“Some people have enough plaques and tangles in their brains to have a postmortem diagnosis of Alzheimer’s disease, but they do not develop clinical dementia in their lifetime,” said Klodian Dhana, MD, PhD, lead author of the paper and an assistant professor in the Division of Geriatrics and Palliative Medicine in the Department of Internal Medicine at Rush Medical College .

“Some have the ability to maintain cognitive function despite the accumulation of these pathologies in the brain, and our study suggests that the MIND diet is associated with better cognitive functions independently of brain pathologies related to Alzheimer’s disease.

In this study, the researchers examined the associations of diet—from the start of the study until death—brain pathologies and cognitive functioning in older adults who participated in the Rush Alzheimer’s Disease Center’s ongoing Memory and Aging Project, which began in 1997 and includes people living in greater Chicago. The participants were mostly white without known dementia, and all of them agreed to undergo annual clinical evaluations while alive and brain autopsy after their death.

The researchers followed 569 participants, who were asked to complete annual evaluations and cognitive tests to see if they had developed memory and thinking problems. Beginning in 2004, participants were given an annual food frequency questionnaire about how often they ate 144 food items in previous year.

Using the questionnaire answers, the researchers gave each participant a MIND diet score based on how often the participants ate specific foods. The MIND diet has 15 dietary components, including 10 “brain-healthy food groups” and five unhealthy groups—red meat, butter and stick margarine, cheese, pastries and sweets, and fried or fast food.

To adhere to and benefit from the MIND diet, a person would need to eat at least three servings of whole grains, a green leafy vegetable and one other vegetable every day—along with a glass of wine—snack most days on nuts, have beans every other day or so, eat poultry and berries at least twice a week and fish at least once a week. A person also must limit intake of the designated unhealthy foods, limiting butter to less than 1 1/2 teaspoons a day and eating less than a serving a week of sweets and pastries, whole fat cheese, and fried or fast food.

Based on the frequency of intake reported for the healthy and unhealthy food groups, the researchers calculated the MIND diet score for each participant across the study period. An average of the MIND diet score from the start of the study until the participant’s death was used in the analysis to limit measurement error. Seven sensitivity measures were calculated to confirm accuracy of the findings.

“We found that a higher MIND diet score was associated with better memory and thinking skills independently of Alzheimer’s disease pathology and other common age-related brain pathologies. The diet seemed to have a protective capacity and may contribute to cognitive resilience in the elderly.” Dhana said.

“Diet changes can impact cognitive functioning and risk of dementia, for better or worse,” he continued. “There are fairly simple diet and lifestyle changes a person could make that may help to slow cognitive decline with aging, and contribute to brain health.

Why you shouldn’t make a habit of doing a ‘just in case’ wee — and don’t tell your kids to either

Why you shouldn’t make a habit of doing a ‘just in case’ wee — and don’t tell your kids to either

September 20, 2021 3.51pm AEST


  1. Jennifer King Honorary Clinical Lecturer, University of Sydney

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Jennifer King is the chair of the Education Committee of the International Urogynecology Association and state chair of the NSW Continence Foundation. The positions are unpaid.


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A woman looks at a toilet sign in an airport.

We’ve all done done a quick “just in case” wee before heading out or because we’re passing the bathroom. If you’re a parent, you might have also told the kids to “do a wee now so we don’t have to find a toilet later.”

Doing a “just in case” wee isn’t a problem if it’s just occasional and if you have normal bladder function.

But doing it too often, making a lifetime habit of it, can kick off a vicious cycle. You can end up training your bladder to “think” it needs to go when it’s only slightly full. And the problem can worsen over time.

If you’re always ducking to the loo to wee at even the slightest tingling sensation, have a go at resisting that first urge — and consider seeing your GP or a pelvic floor physiotherapist about it.

Read more: Curious Kids: why is urine yellow?

Your bladder can probably hold more than you think

Most bladders are actually capable of holding quite a lot of fluid.

For those with normal bladders (that is, you haven’t been diagnosed as having an overactive or irritable bladder), every day capacity is between 400–600 mls. It should take about two hours for the water you drink to make its way to the bladder.

So if you drink a 600ml bottle of water, it would be perfectly reasonable not to actually need to go to the toilet until a couple of hours later. In reality, however, I know of people who say they drink just a small amount and head off to the bathroom shortly after.

What happens if you get into the ‘just in case’ habit?

To pass urine easily, we need the bladder muscle to contract and the muscles around the urethra and pelvic floor to relax.

This nice, coordinated pattern does not occur nearly as well if there is no real urge to void. You’ll probably be able to squeeze some urine out, but it’s not how the muscles are supposed to work.

The bladder’s response is to spasm and contract more aggressively and inappropriately.

The bladder gets used to holding a certain amount and if you are always emptying at that amount, it gets harder to hold more. The bladder “thinks” it is at capacity, when it is not. You end up with a pattern of uncoordinated emptying.

The good news is most people with a normal bladder can train themselves out of this habit. It’s about learning to recognise the signs and differentiate between a small urge and a real need.

You don’t need to run off at the first urge — have a go at resisting it and see what happens.

Of course, nobody is saying you should hold on until you feel absolutely tortured. If ignoring the first urge is causing real distress, you should talk to your GP or a pelvic floor physiotherapist.

Let your kids go to the toilet when they actually need to

Everyone remembers the kids who wet their pants at school or those who were always in trouble “because they should have gone to the toilet at recess”.

In fact, it’s better just to let kids go to the toilet when they need to, instead of berating them about not having gone at recess or “before we left”.

You can cause more damage (physical and psychological) in the long run if you give kids a hard time about toileting, load it with emotion, or train them into the habit of always going “just in case”. Don’t always prompt them to go to the toilet.

(In some situations, such as with people with dementia, it can be appropriate to prompt people to go to the toilet. But this is done after a reasonable number of hours when there should be a good amount of urine in the bladder. And it is a compromise arrangement where we try to minimise incontinence episodes and patient distress.)

A parent talks to her child.
It’s better just to let kids go to the toilet when they need to, instead of berating them about not having gone at recess or ‘before we left’. Shutterstock

Not everyone has a ‘normal’ bladder

The aim with toilet training is to learn to recognise the sensation of bladder filling and gradually develop the ability to resist bladder emptying until convenient and socially appropriate.

But for some people this is never completely or consistently achieved.

Many people – perhaps 30% of adults and large numbers of children – do not have a normal bladder. Rather, they have an overactive or irritable bladder.

This can make people want to go all the time or cause sudden urgency. They may not always make it to the toilet quickly enough. It can be impossible to prevent bladder leakage. Some people cope by limiting fluids or forever going “just in case”.

As with all bladder problems, it’s more common for women than men and tends to become more troublesome as we age.

Overactive bladders are unlikely to spontaneously improve. A good place to start would be to talk with your GP, a continence nurse or a specialist physiotherapist. These bladders need to be retrained using techniques learned from a specialist physio. Medication can sometimes help.

For most of us, though, overly frequent visits to the loo, or going “just in case” is a habit worth quitting.

Read more: Health Check: how do I tell if I’m dehydrated?

Dry Eyes Afflict Many of Us. Here’s What to Do About It.

Personal Health

From The New York Times.

Dry Eyes Afflict Many of Us. Here’s What to Do About It.

That gritty, itchy feeling in your eyes can arise from many causes, including too much screen time, and eye drops may only make it worse.

Jane E. Brody

By Jane E. BrodySept. 20, 2021, 5:00 a.m. ETLeer en español

I didn’t have to wait until my ninth decade to appreciate how annoying dry eyes can be. And I was flummoxed by the plethora of products on pharmacy shelves that promise relief for a problem that affects about one in five adults. Perhaps you, like me, are among the many who have tried various over-the-counter remedies that didn’t help or sometimes made matters worse.

Dry eye problems become increasingly prevalent with age. But since my mid-30s, I’ve been coping with a mild form of this condition and, despite intermittent visits to health professionals, have gotten only limited relief. With all the “extra” time I had to read for pleasure during the pandemic, the gritty feeling in my chronically dry eyes rendered this diversion anything but pleasant. Other common complaints linked to dry eyes include itching and undue sensitivity to sun and bright lights, all of which I suffer from.

In an online survey published in January, two thirds of respondents reported having symptoms of dry eye, and of those, more than a quarter said their symptoms were made worse by wearing a face mask. But Dr. Ira Udell, a professor of ophthalmology at the Zucker School of Medicine at Hofstra/Northwell, said that while masks may indeed cause ocular discomfort, an association between mask-wearing and dry eye per se is unlikely, given that exhaled moisture when wearing a mask fogs glasses and, if anything, the increased humidity would raise moisture levels around the eyes.

A more likely explanation of those findings is an association between dry eyes and pandemic-related stress. In two studies of veterans, researchers found strong links between dry eye syndrome, post-traumatic stress disorder and depression.

What causes dry eyes?

I’ve recently learned just how complicated it can be to keep my eyes moist and free of irritating dryness, a need made more challenging by an ever-greater reliance on screens for work and play. When people stare at computer screens for hours on end, they blink less often, resulting in tired, distressed and dry eyes.Sign up for the Well Newsletter  Get the best of Well, with the latest on health, fitness and nutrition. Get it in your inbox.

Inadequate lubrication of the ocular surface can also result in blurry vision, a symptom that has repeatedly prompted me to get my vision checked, only to find that my current prescription hasn’t changed even though words on a page are less clear.

Although dry eye problems are most common in people over 50, they’re also increasing among young adults, which experts attribute to the ubiquity of smartphones and computers. Younger people are also more likely to wear contact lenses, prolonged wearing of which may also cause dry eye.

Dry eye is a hallmark symptom of Sjögren’s syndrome and other autoimmune disorders that impair the body’s lubricating tissues. Dry eye also commonly occurs temporarily following cataract surgery; Lasik eye surgery, which reshapes the cornea to improve vision; and blepharoplasty, an operation to correct drooping eyelids.

Some people develop chronically dry eyes because their lids don’t close completely during sleep. If you suspect this may be your problem and you live alone, you might invite a visitor to check your eyes when you’re asleep, Dr. Udell suggested. A cellphone photo would be useful to show to your doctor.

How does the eye stay lubricated?

Think of the tear film that coats and lubricates the eye as a three-layer sandwich, with each layer produced by different glands. The meibomian glands in the upper and lower eyelids create an oily outer layer that stabilizes the film. If the film breaks up too quickly, blurry vision is the likely result. Next are two sets of lacrimal glands that supply the watery tears. Innermost is the mucin layer that attracts water and helps to spread the tear film over the surface of the cornea. Even if the tear supply is adequate, a mucin deficiency can impede wetting of the cornea and damage its surface.

Both the meibomian and lacrimal glands have receptors for the sex hormones, androgen and estrogen, and a decrease in hormone levels likely explains why dry eye problems increase in women at menopause and in men who are treated with anti-androgen therapy for prostate cancer. Indeed, the most common cause of dry eye is evaporation of moisture from the eyes from dysfunction of the meibomian glands that results in instability of the tear film.

Sometimes the attempted solution, like using multiple-use eye drops that contain preservatives, can actually make eye irritation worse. I ended up with chronically red eyes after using such drops, and the problem soon resolved when I switched to single-use lubricants that were preservative-free. While single-dose eye drops are only approved for a one-time use, Dr. Udell said that it’s usually safe to use them for up to two days if you want to cut down on cost and waste, as long as the tip isn’t touched and is covered after each use.

Medications that treat other conditions can interfere with adequate tear production. Common culprits include antihistamines, beta blockers, oral contraceptives, diuretics and drugs used to treat Parkinson’s disease, anxiety disorders, asthma, chronic obstructive pulmonary disease (C.O.P.D.) and abnormal heart rhythms.

Environmental conditions that can exacerbate dry eye problems include smoky or excessively dry air, which can result from indoor heating and air conditioning. Long before the pandemic, I began wearing eyeglasses when outdoors, especially on windy days and always when riding my bicycle, to protect my eyes from dryness and grit. A variety of glasses are available to block out wind, glare and airborne irritants.

If you swim, be sure to wear goggles to prevent salty or chemically treated water from irritating your eyes.

Another practical measure that Dr. Udell emphasized is applying warm compresses to the eyelids morning and night to assist meibomian gland function. I gently wash my eyelids from the nose outward with a warm washcloth every night. Repeat the washcloth cleanse if you wake up in the morning with “sleep in your eyes,” then apply artificial tears.

Use of artificial tears several times a day is essential for most cases of dry eye. Although no product precisely mimics the composition of natural tears, many are helpful if used regularly, Dr. Udell said. He suggested trying various products one at a time to find one that is most effective for you. You could start with a low-cost generic product and, if that doesn’t help, try the brand name version, he said.

However, if over-the-counter remedies and the practical measures described above fail to bring adequate relief, consult an eye specialist. There are prescription products and special glasses that create a high-humidity moisture chamber around the eyes, among other remedies, for severe cases of dry eye.

Jane Brody is the Personal Health columnist, a position she has held since 1976. She has written more than a dozen books including the best sellers “Jane Brody’s Nutrition Book” and “Jane Brody’s Good Food Book.”

Medicinal cannabis to manage chronic pain? We don’t have evidence it works


Medicinal cannabis to manage chronic pain? We don’t have evidence it works

March 23, 2021 5.52am AEDT


  1. Michael Vagg Conjoint Clinical Associate Professor, Deakin University School of Medicine and Specialist Pain Medicine Physician, Deakin University

Disclosure statement

Michael Vagg is currently the Dean of the Faculty of Pain Medicine, Australian and New Zealand College of Anaesthetists. In the last 5 years, payments from pharmaceutical companies for providing educational talks to medical practitioners or other honoraria have constituted less than 0.05% of his gross income. No advisory or marketing advice has been given to the pharmaceutical industry in that time. NPS Medicinewise has paid A/Prof Vagg for consultative services to develop educational materials regarding prescription of pain medications.


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As a pain specialist, I often have patients asking me whether they should try medicinal cannabis. There’s a common perception it can be an effective way to manage chronic pain.

But two expert groups have recently recommended against medicinal cannabis for people suffering persistent non-cancer pain.

The International Association for the Study of Pain published a position statement last week after its presidential taskforce summarised the evidence on the topic.

And yesterday the Faculty of Pain Medicine of the Australian and New Zealand College of Anaesthetists published guidance for health practitioners in the form of a Choosing Wisely recommendation. (Choosing Wisely is an initiative of NPS Medicinewise which aims to highlight low-value health care.)

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Many in the community would see this recommendation as controversial. So let’s take a look at some of the commonly held misconceptions about medicinal cannabis and chronic pain.

Myth #1: evidence shows cannabis products are effective for chronic pain

Evidence from randomised controlled trials is critically lacking when it comes to medicinal cannabis products for chronic pain.

While some studies have looked at tetrahydrocannabinol (THC, the main psychoactive component of cannabis) or a combination of THC and cannabidiol (CBD), there isn’t a single published randomised controlled trial of a CBD-only product for chronic pain of any type. Australian medicinal cannabis products are often CBD-only.

This means we can’t even judge whether the claims that medicinal cannabis can alleviate pain might be true. The results of THC-containing products in clinical trials don’t give a reliable picture one way or the other because they involve too few participants, have major technical flaws in design, or have been judged to have an unacceptably high risk of producing biased results.

The International Association for the Study of Pain taskforce looked at all the available research published in peer-reviewed journals on the use of medicinal cannabis for pain management, from preclinical studies to human trials.

They concluded overall the studies’ “quality, rigour, and transparency of reporting” of benefits and harms needs to be improved across the board. We would require higher quality data, for example through randomised controlled trials, to determine the safety and efficacy of using medicinal cannabis for pain.

In the polite and understated world of academic medicine, this is about as big a smackdown as it gets. The authors are essentially saying most of the studies are too poorly done, using unsuitable methods, to give any answer to the most basic question of whether medicinal cannabis helps with pain.

Read more: Medicinal cannabis users in Victoria could soon be allowed to drive with THC in their system. Is it safe?

Myth #2: cannabis products should be provided as a ‘last resort’

A doctor has the right to prescribe any drug they think may be effective for an individual patient based on nothing more than their clinical judgement. We do this relatively frequently, especially for chronic pain.

This is ethical if we have a scientific reason to believe the drug may be helpful. But for patients with chronic pain, we have little reason to believe medicinal cannabis offers any sustained benefit.

A further challenge to the ethical provision of cannabis products as a “last resort” is the fact they’re among the most expensive pharmaceutical products available to chronic pain patients, many of whom have very modest incomes. The only party likely to benefit is the manufacturer.

A senior man talks with a doctor.
Many people who experience chronic pain believe medicinal cannabis could help. Shutterstock

Myth #3: medical cannabis may help with the opioid crisis

There’s a consensus that much of the current use of opioid analgesics to manage chronic non-cancer pain in Australia may be of limited value.

Proponents of medicinal cannabis have suggested it may hold promise as a potential solution to this problem. While this idea has some appeal, the balance of the evidence points the other way.

Read more: 1 in 10 women with endometriosis report using cannabis to ease their pain

Data collected from Australia and New Zealand shows participation in best-practice multidisciplinary pain care, as provided by a specialist pain clinic, results in half of pain patients being able to reduce their opioids by at least 50%, with improved quality of life.

People wanting an alternative to opioid treatment for persistent pain will do best if they seek out treatment from a professional team of experts, rather than substituting cannabis for opioids.

It could be harmful

The International Association for the Study of Pain taskforce identified general known risks from using cannabis, such as in recreational settings. But no studies have characterised the way the body handles prescribed or over-the-counter medicinal cannabis products.

The TGA guidance document on medicinal cannabis notes basic research on how the drugs interact with both the body and other medications — known as pharmacokinetic and pharmacodynamic studies — is not available. Without this information, we can’t answer important questions about the safety of medicinal cannabis.

A collection of white round pills.
Medicinal cannabis isn’t the solution to the opioid crisis. Shutterstock

Medicinal cannabis products may have a role in the management of other conditions, such as relieving chemotherapy-induced nausea, or treating childhood epilepsy. The evidence around those conditions seems to be more convincing than the studies for persistent pain, though I’m not an expert in either field.

Despite the lack of evidence to support the use of medicinal cannabis for chronic pain, the legislation around medicinal cannabis in Australia continues to become more permissive.

It will be legal to sell low-dose CBD products over the counter from June this year, if they meet the very minimal requirements to be listed by the Therapeutic Goods Administration (TGA).

Meanwhile, Tasmania is set to become the last Australian state to allow GPs to prescribe medicinal cannabis from July.

Read more: Weed withdrawal: More than half of people using medical cannabis for pain experience withdrawal symptoms

The Faculty of Pain Medicine has a track record of advocacy for pain patients. We led the process that resulted in the first ever National Pain Strategy a decade ago, and were a founding partner of Painaustralia as an ongoing policy voice.

If medicinal cannabis was truly as potentially valuable as often claimed, we would be the loudest voice in favour of wider access. The weight of evidence points us away from this conclusion.

Why are we seeing more COVID cases in fully vaccinated people? An expert explains

Naron Sangnak/EPA/AAP

Why are we seeing more COVID cases in fully vaccinated people? An expert explains

September 8, 2021 4.57pm AEST


  1. Nathan Bartlett Associate Professor, School of Biomedical Sciences and Pharmacy, University of Newcastle

Disclosure statement

Nathan Bartlett does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.


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Many people are worried about reports of “breakthrough” COVID-19 infections overseas, from places like Israel and the United States.

A breakthrough infection is when someone tests positive for COVID after being fully vaccinated, regardless of symptoms.

The good news is most breakthrough infections usually result in mild symptoms or none at all, which shows us that vaccines are doing exactly what they’re supposed to do — protecting us from severe disease and death. Vaccines aren’t designed to protect us from getting infected at all (known as “sterilising immunity”).

People with breakthrough infections can go on to infect others. Preliminary evidence indicates immunised people can have high levels of virus in the nose, potentially as high as unvaccinated people.

However, if you’re vaccinated you’ll clear the virus more quickly, reducing the length of time you’re infectious and can pass the virus on.

Here’s why breakthrough cases are happening, and why you shouldn’t worry too much.

Waning immunity

Two studies from the United Kingdom suggest the immunity we get from COVID vaccines wanes over time, after about four to six months.

While the more-infectious Delta variant continues to circulate, waning immunity will lead to more breakthrough infections.

But the reduction isn’t large currently. Vaccine effectiveness is very high to begin with, so incremental reductions due to waning won’t have a significant effect on protection for some time

Israeli data shows some vaccinated people are becoming ill with COVID. But we need to keep in mind Israel’s vaccine rollout began in December 2020, and the majority of the population were vaccinated in early 2021. Most are now past six months since being fully vaccinated.

Given most people in Israel are vaccinated, many COVID cases in hospital are vaccinated. However, the majority (87%) of hospitalised cases are 60 or older. This highlights what’s known about adaptive immunity and vaccine protection — it declines with age.

Therefore we’d expect vulnerable groups like the elderly to be the first at risk of disease as immunity wanes, as will people whose immune systems are compromised. Managing this as we adjust to living with COVID will be an ongoing challenge for all countries.

What would be concerning is if we started seeing a big increase in fully vaccinated people getting really sick and dying — but that’s not happening.

Globally, the vast majority of people with severe COVID are unvaccinated.

Read more: COVID cases are rising in highly vaccinated Israel. But it doesn’t mean Australia should give up and ‘live with’ the virus

We’ll probably need booster doses

Waning immunity means booster doses will likely be needed to top up protection, at least for the next couple of years while the virus continues to circulate at such high levels.

Our currently approved vaccines were modelled on the original strain of the virus isolated in Wuhan, not the Delta variant, which is currently dominant across most of the world. This imperfect match between vaccine and virus means the level of protection against Delta is just a little lower.

Read more: What’s the Mu variant? And will we keep seeing more concerning variants?

Because the level of effectiveness is so high to begin with, this small reduction is negligible in the short term. But the effects of waning over time may lead to breakthrough infections appearing sooner.

mRNA vaccines in particular, like Pfizer’s and Moderna’s, can be efficiently updated to target prevalent variants, in this case Delta. So, a third immunisation based on Delta will “tweak”, as well as boost, existing immunity to an even higher starting point for longer-lasting protection.

We could see different variants become endemic in different countries. One example might be the Mu variant, currently dominant in Colombia. We might be able to match vaccines to whichever variant is circulating in specific areas.

The dose makes the poison

Your level of exposure to the virus is likely another reason for breakthrough infections.

If you’re fully vaccinated and have merely fleeting contact with a positive case, you likely won’t breathe in much virus and therefore are unlikely to develop symptomatic infection.

But if you’re in the same room as a positive case for a long period of time, you may breathe in a huge amount of virus. This makes it harder for your immune system to fight off.

This may be one reason we’re seeing some health-care workers get breakthrough infections, because they’re being exposed to high viral loads. They could be a priority for booster doses.

Might unvaccinated kids be playing a role?

It’s unclear if children are contributing to breakthrough infections.

Vaccines aren’t approved for young children yet (aged under 12), so we’re seeing increasing cases in kids relative to older people. Early studies, before the rise of Delta, indicated children didn’t significantly contribute to transmission.

More recent studies in populations with vaccinated adults, and where Delta is the dominant virus, have suggested children might contribute to transmission. This requires further investigation, but it’s possible that if you’re living with an unvaccinated child who contracts COVID, you’re likely to be exposed for many, many hours of the day, hence you’ll breathe in a large amount of virus.

The larger the viral dose, the more likely you’ll get a breakthrough infection.

Potentially slowing the number of breakthrough infections is one reason to vaccinate 12 to 15 year olds, and younger children in the future, if ongoing trials prove they’re safe and effective in this age group. Another is to protect kids themselves, and to get closer to herd immunity (if it’s achievable).

Read more: High priority: why we must vaccinate children aged 12 and over now

A silver lining

Breakthrough infections likely confer extra protection for people who’ve been fully vaccinated — almost like a booster dose.

We don’t have solid real-world data on this yet, but it isn’t surprising as it’s how our immune system works. Infection will re-expose the immune system to the virus’ spike protein and boost antibodies against the spike.

However, it’s never advisable to get COVID, because you could get very sick or die. Extra protection is just a silver lining if you do get a breakthrough infection.

As COVID becomes an endemic disease, meaning it settles into the human population, we’ll need to keep a constant eye on the interaction between vaccines and the virus.

The virus may start to burn out, but it’s also possible it might continually evolve and evade vaccines, like the flu does.

Read more: How will Delta evolve? Here’s what the theory tells us

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Dementia: how to make sense of the link with people who struggle to hear over background noise

Dementia: how to make sense of the link with people who struggle to hear over background noise

August 25, 2021 2.24am AEST


  1. Thomas Littlejohns Senior Epidemiologist, University of Oxford

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Thomas Littlejohns does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.


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Old woman looking isolated in a public place
‘I can’t hear what anyone is saying.’ Christian Langballe/Unsplash, CC BY-SA

The number of people living with dementia is projected to treble from 50 to 150 million worldwide by 2050. Although there’s currently no cure for the condition, researchers are continuing to learn about how people can reduce their risk through making lifestyle changes (such as exercising more or quitting smoking) and managing health issues (including diabetes and hypertension).

Hearing loss may also be a potential target for preventing dementia. Studies show that hearing impairment is linked to a greater risk of dementia – and that managing hearing problems early may be key to reducing risk.

Our recent paper confirmed these findings, while focusing on an area that has received less attention: people who struggle to pick out speech in noisy environments. The hearing of people in this category is often deemed “normal” in traditional tests, but we were able to show with a large cohort for the first time that they too are at greater risk of going on to develop dementia.

Speech-in-noise impairments

Previous studies looking at the link between hearing impairment and dementia have used a method of hearing assessment known as pure-tone audiometry to measure participants’ hearing. This is usually the gold standard to testing a person’s hearing, and works by measuring a person’s ability to detect sounds – specifically tones – in a quiet environment.

However, many people whose test shows that they have “normal” hearing can still have issues hearing when different assessment methods are used. This includes those who struggle to pick out speech in noisy places, which is known as speech-in-noise hearing.

Speech-in-noise hearing is akin to the kind of hearing we do in everyday life. To find out whether speech-in-noise hearing impairment was similarly linked with increased dementia risk, we looked at data from a total of 82,039 people aged 60 or over.

Participants’ speech-in-noise hearing was measured using what’s known as a digits triplet test. This involved asking participants to identify three spoken numbers presented in varying levels of background noise. Based on their performance, we then grouped participants into three categories: “normal”, “insufficient” and “poor”.

Participants were followed up over 11 years to see who developed dementia. A total of 1,285 people from the 82,039 total received a dementia diagnosis over that period. We found those with insufficient and poor speech-in-noise hearing had a 61% and 91% greater risk of developing dementia compared to those with normal speech-in-noise hearing. The dementia risk of those with poor speech-in-noise hearing was virtually identical to what previous studies found about people with hearing impairments that are picked up by pure-tone audiometry.

Liverpool Street Station in London as crowds of people rush through.
Struggling to hear an announcement in a busy place is one sign of poor speech-in-noise hearing. Keith Gentry/ Shutterstock

Finding the cause

There are several suggestions for why there is a link between hearing impairment and dementia. One possibility is that impaired hearing increases the likelihood of other risk factors for dementia, such as social isolation or depression. But we found little evidence to support this, with depressive symptoms and social isolation only explaining a small percentage (less than 7%) of the association between speech-in-noise hearing impairment and dementia.

It’s also possible that our findings (and those from other studies) might be detecting an association between dementia and hearing impairment when in fact both are caused by something else altogether. While we took a range of factors into account in our analyses – such as age, education level and socioeconomic status – we can’t rule out the possibility that other factors might be involved that we didn’t look at.

The other possibility is that dementia causes hearing impairment. This might seem an unusual explanation, as in our study dementia was diagnosed after hearing was measured. But the pathology of dementia typically develops years before a person receives a diagnosis. It often occurs before memory problems and other cognitive issues become apparent. This “pre-clinical” pathology results in other symptoms – such as weight loss – and could potentially cause issues with hearing.

We explored this possibility in two ways. The first was to see whether hearing impairment was associated with dementia diagnosed a long time after hearing was measured. This is because pre-clinical symptoms are more likely to manifest close to a diagnosis.

When looking at dementia diagnosed nine to 11 years after the hearing test, insufficient and poor speech-in-noise hearing was associated with a 54% and 85% increased risk of dementia. This is similar to the main findings of our study. You would have expected this group to have a lower correlation with hearing problems if pre-clinical dementia was causing them.

Our second approach was to only include people who described their health as “good”, “very good” or “excellent” at the time hearing was measured. This is because worse health might reflect the early pre-clinical symptoms of dementia. People with worse health are also probably more likely to have hearing problems.

Again, the number of people in this group who went on to develop dementia after being identified with a hearing impairment was similar to those of our initial findings. Had dementia been causing the impairment, you might have expected a disproportionately high number of those who went on to develop dementia to have been the ones already reporting generally poor health.

In both cases, this is tentative evidence that dementia might not be causing hearing impairment. But even so, some early pre-clinical symptoms of dementia can manifest decades before a diagnosis. Studies which diagnose dementia 15 or even 20 years later are necessary to disentangle these complex relationships further.

While our findings are preliminary, they add to the growing body of evidence that hearing impairment is a promising target for preventing dementia. In fact, it’s thought that if hearing impairment is indeed a cause of dementia, addressing it could prevent 8% of dementia cases in instances where dementia is not otherwise evident. This statistic is based on pure-tone audiometry hearing – so it could very well be higher when considering issues with speech-in-noise hearing.

Can you transmit allergies?

Don’t fool around with these nuts

After eating Brazil nuts 2-3 hours prior, a man had unprotected intercourse with his 20-year-old partner who had a documented Brazil nut allergy. The woman developed urticaria, angioedema, and dyspnea. To figure out the cause of this hypersensitivity reaction, UK researchers did a skin prick test in the woman using the boyfriend’s semen both before and after eating Brazil nuts.

Apparently, some nut protein got into the semen. 

“We believe this to be the first case of a sexually transmitted allergic reaction,” the researchers wrote in the Journal of Investigational Allergology and Clinical Immunology. Of note, Brazil nuts are the second most frequent nut allergy in the United Kingdom. Unfortunately for science, the couple broke up before the investigators could confirm the results.

“Our demonstration of an allergenic Brazil nut protein in the semen clearly proves the ability of such protein(s) to resist digestion. Additionally, to enter the semen, the protein would require circulation in the blood to the prostate or other reproductive organ.”

Notably, severe allergic reactions have been demonstrated in those with crustacean allergy following exposure from kissing. Also, penicillin exposure leading to allergic reaction could occur secondary to intercourse, per the literature.

The moral of this study? If you have food allergies, you might want to find out what your partner recently ate, before you get too close

Supporting menstrual health in Australia means more than just throwing pads at the problem

Supporting menstrual health in Australia means more than just throwing pads at the problem

August 27, 2021 1.02pm AEST


  1. Erin C. Hunter Lecturer in Global Health, University of Sydney
  2. Julie Hennegan Senior Research Fellow, Burnet Institute

Disclosure statement

Erin C. Hunter has received funding for research on menstrual health. She has conducted menstrual health research funded by the Bill & Melinda Gates Foundation, Grand Challenges Canada, and The Johns Hopkins Center for Qualitative Studies in Health and Medicine. She is currently an investigator on a National Health and Medical Research Council grant to study menstrual health in Myanmar.

Julie Hennegan has received funding for research on menstrual health. This has included from foundations (The Case for Her, Bill & Melinda Gates Foundation) and research councils (she is currently an investigator on a National Health and Medical Research Council grant developing a menstrual health intervention in Myanmar). She led the development of the definition of Menstrual Health as part of the Terminology Action Group of the Global Menstrual Collective.


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Menstruation has recently had a bit of a moment in Australia.

The Victorian and South Australian governments are now providing free pads and tampons in government schools, while New South Wales is trialling a pilot program to do the same.

Attention to menstruation is exciting and long overdue. But hurried efforts to provide free pads are not enough, particularly after decades of policy neglect.

To truly meet the needs of women, adolescent girls, and all people who menstruate, we must ask smart questions and develop evidence-based strategies for the long term.

Get your news from people who know what they’re talking about.

What is menstrual health and how do we achieve it?

This year, a collaboration of global stakeholders and experts defined menstrual health as a state of complete physical, mental and social well-being in relation to the menstrual cycle.

The authors also shed light on the breadth of menstrual health needs. These extend well beyond access to pads, and highlight a number of things we need to consider if we’re going to better support menstrual health in Australia.

1. Information about the menstrual cycle

Knowledge about menstrual biology, reproduction and self-care practices is important. Understanding the body helps prevent distress and facilitates informed decision-making. This might include choice of menstrual product or decisions to seek medical support for period-related difficulties.

Studies in high-income countries have found women and girls don’t have enough information about menstruation, and research on menstrual disorders in Australia has found deficits in menstrual health literacy.

So we must ensure adolescents have comprehensive and timely education about menstruation in schools to promote body literacy and support their menstrual health.

A teenage girl sits looking out a window.
Research has found women and girls don’t necessarily have all the information they need when it comes to menstruation. Shutterstock

2. Materials and facilities to care for the body

Beyond having enough products to manage a period, menstrual health requires supportive spaces to change products, dispose of single-use materials (for example, pads and tampons) or wash reusable products (for example, menstrual cups). Spaces need to be comfortable and private.

In high-income countries, little attention has been given to whether school and workplace facilities are adequately meeting these needs. This is especially relevant as reusable products such as menstrual underwear and cups are growing in popularity.

3. Diagnosis, care and treatments for discomforts and disorders

Pleasingly, we’ve seen menstrual health research and action focusing on disorders, with endometriosis receiving increased investment in the most recent federal budget.

But 92% of adolescents and young women in Australia report painful periods.

We need to see comprehensive policy that acknowledges the breadth of menstrual needs, and the varied levels of pain and discomfort associated with menstruation.

Read more: I have painful periods, could it be endometriosis?

4. Positive and respectful environments

Menstruation continues to be stigmatised around the world. Social pressure to hide any sign of menstruation can dissuade girls and women from talking about their experiences or seeking support and advice. This can harm well-being.

Family members, education institutions, workplaces and government policies all have a role to play in creating environments that support those who menstruate.

For example, freedom to visit the toilet during the school day or to work flexibly around period pain can shape experiences of menstruation.

What’s the impact of unmet menstrual health needs?

A survey of young people in New Zealand found 8% reported missing school due to a lack of menstrual products.

A review of multiple studies estimated 12% of young women in high-income countries have missed school or university because of period pain.

We know from research in low-, middle-, and high-income countries there are a variety of other consequences of unmet menstrual health needs for physical, mental and social well-being.

But we have more to learn about the magnitude of these issues across populations and sub-groups.

Read more: Imagine having your period and no money for pads or tampons. Would you still go to school?

Providing free menstrual products may seem like a “silver bullet”. But evidence from low- and middle-income countries has shown providing such products is not enough to improve menstrual health.

This is also likely to be the case in high-income countries like Australia where stigma and inadequate education around menstruation remain challenges.

A woman holds a menstrual cup and a tampon.
Pads and tampons are no longer the only way to manage periods. Shutterstock

What are we overlooking?

A narrow focus on providing pads and tampons also risks suppressing menstrual product choice, and overlooks opportunities to support more environmentally friendly options.

Policies in Australia focus on providing single-use products, which are not very good for the environment. A menstruating person will use thousands of disposable pads and tampons over their lifetime — a large proportion of which is plastic waste.

Technologies such as menstrual underwear, reusable pads and menstrual cups present environmentally and economically sustainable alternatives. The median cost of a menstrual cup is A$32 and it can be used for up to ten years: that’s just 25 cents per period.

Australian adolescents’ feelings about reusable products remain largely unexplored. If research shows they’re receptive to these options, funding could be directed accordingly.

For example, installing wash basins or toilet hoses inside toilet cubicles in schools could facilitate the use of menstrual cups.

Read more: It’s time to teach the whole story about ovulation and its place in the menstrual cycle

Menstruation matters

To inform effective policy responses, we need robust research exploring menstrual health needs in Australia and the extent to which these contribute to broader health and education outcomes.

And if we are to sustain the support of governments over the long term, we need evidence of what works. We must invest in developing effective responses and commit to evaluating the effects of our policies in supporting girls, women and all people who menstruate.