Every month the ABC receives thousands of questions about COVID-19 from our readers, and this month has been no exception.
Many of you have asked questions about the new BA.2 Omicron variant, and why some people just don't seem to catch COVID-19 despite being exposed.
Scroll down to read, or click on a link below to jump to the answer.
- Why do some people not seem to get COVID-19 despite exposure?
- What do we know about long COVID?
- Is the new BA.2 Omicron variant more infectious or more deadly than Omicron?
- Is it a good idea to remove mask mandates?
- Why do some Australians remain unvaccinated?
Why do some people not seem to get COVID despite exposure?
A person's immunity to COVID-19 is influenced by multiple factors and everyone's immune system is different, immunologist and scientist Vanessa Bryant says.
"Some people might generate an immune response that just makes better antibodies … and we do think this is largely genetic," she said.
Dr Bryant is studying the transmissibility of COVID-19 among household contacts to better understand the virus and how we respond to it.
Of course, vaccination is an essential tool against catching COVID-19 and the most effective way to protect yourself from getting sick.
But the effectiveness of COVID-19 vaccines wanes over time, and the speed at which this happens — and when a person might become vulnerable to a breakthrough infection — depends on the vaccine, the variant and the individual.
Previous COVID-19 infections can also impact levels of immunity, and research has found that people with higher levels of memory T-cells from other coronavirus infections — ie those responsible for common colds — are less likely to become infected with SARS-CoV-2.
Experts say there may also be particular genetic and immunological features that mean some people are naturally more resistant to COVID-19.
Researchers hope that identifying key genetic changes in people who are resistant will lead to the development of more effective drug therapies.
What do we know about long COVID and who is more likely to get it?
Generally long COVID is thought of as the persistence (or emergence) of symptoms at least three months after a SARS-CoV-2 infection.
Symptoms can include:
- Crippling fatigue
- Brain fog
- Headaches
- Loss of smell
- Hair loss
- Other physically debilitating symptoms such as vertigo, pain and numbness
- Scarring of the lungs
David Putrino, an Australian physiotherapist researching long COVID in the United States, says the majority of the 2,000 patients he is treating had previously been fit and healthy.
Many of them had previously been involved in recreational sport, engaging in running marathons and exercising daily.
The physiotherapist, who has a PhD in neuroscience, says the average age of his patients is 42.
"Now, as a result of their long COVID symptoms, all of that has been taken away from them to the point where they're really struggling just to manage their daily life on a regular basis," he said.
It's estimated that 10 to 30 per cent of people infected with the coronavirus may develop long-term symptoms.
It remains unclear who will and who won't end up with long COVID.
"What we do know is that people who have long COVID are starting to show signs and symptoms that are consistent with people with autoimmune disorders, and so we do think that the immune system is at play here," he said.
Dr Putrino's advice is to do everything to avoid contracting the illness, including getting vaccinated and keeping up to date with recommended booster shots.
There is no specific treatment for this condition. And for now, the treatment revolves around relieving patients' symptoms.
Is the new BA.2 Omicron variant more infectious or more deadly than Omicron?
Known as a "stealth" variant, the new Omicron subvariant of the virus, BA.2, is quickly becoming the predominant source of infections.
Omicron has several sub-lineages, with the BA.1 variant accounting for most Omicron cases in New South Wales and worldwide.
However, a UNSW study suggested that BA.2 recently became the most dominant strain in NSW.
The World Health Organization (WHO) says studies have shown the BA.2 variant appears to be more transmissible than BA.1.
UNSW School of Population associate professor James Wood said the new sub-variant was about 25 per cent easier to catch than the original strain.
But the WHO says infection data from South Africa, the UK and Denmark suggests there is no difference between the severity of Omicron's BA.1 and BA.2.
The WHO released a statement calling it a "variant of concern", but Dr Wood said there was no need to be "overly concerned".
"Vaccines seem to work just as well against it," he said.
"We expect people who were infected with Omicron recently will have very good protection against it.
Is it a good idea to remove mask mandates?
Masks have been essential in preventing the spread of COVID-19 because the virus spreads through the air we breathe.
When Queenslanders threw down their masks in March, air quality and health expert Lidia Morawska told the ABC it was too soon to ease mask restrictions.
"Removing masks is not a good idea," said Professor Morawska, who Time magazine last year named one of the 100 most influential people in the world for helping to highlight the airborne spread of COVID-19.
"The number of people infected in the community is very high.
"We haven't taken many other measures to protect people, like improved ventilation in indoor spaces.
"If people are in [close] proximity to each other, even with improved ventilation, infection risk is very high, so mask wearing is a very well protected measure."
Infectious disease expert Paul Griffin said it was still appropriate for masks to be worn in high-risk settings such as health care, aged care and disability support.
Professor Griffin said while it was appropriate to relax restrictions, in reference to Queensland’s move to lift the mask mandate, people should remain vigilant with other COVID-19 safety measures.
"Our reliance on our other mitigation strategies that need to continue is perhaps even more critical now, and by that I mean things like getting tested and staying in if you have symptoms, and of course, being up to date with your vaccination," he said.
Mask mandates in most indoor settings have been relaxed or dropped in New South Wales, Victoria, the ACT and now Queensland. However, they are still compulsory in certain places such as airports, on public transport, in hospitals, disability care centres, prisons and at aged care homes.
It is recommended that people wear face masks when they can't physically distance from others.
Click here, to see the COVID-19 mask rules explained for every state and territory.
Why do some Australians remain unvaccinated?
While Australia now has one of the highest vaccination rates in the world, there are still about 900,000 people over the age of 16 yet to receive a first jab.
There are some Australians who, through consultation with their GP, decide that they can't be vaccinated for medical reasons.
Although, this is very rare.
Vaccine resistance versus vaccine hesitancy
According to Department of Health data provided to The Drum, the number of medical exemptions granted is less than 0.153 per cent of the more than 21 million people who have been vaccinated in Australia. That's about 32,000 people.
And of those, most have only been given temporary exemptions.
Only about 1,200 people have been granted permanent medical exemptions from a COVID-19 vaccine.
Graeme Stewart, director of clinical immunology and allergy at Westmead Hospital, says the only people who should be exempted are those with genuine allergies and a risk of anaphylaxis.
"But those who have that risk from all COVID vaccines are vanishingly rare," he said.
Professor Stewart says there's a need to separate the "vaccine hesitant" from the "vaccine resistant" because they are two very different groups.
Among the hesitant are those that may have previously had bad reactions to vaccines or medications. Some may have underlying health issues or be undergoing treatment for other conditions and be concerned about the side effects a COVID-19 vaccine might cause.
Another large proportion of the remaining unvaccinated cohort in Australia includes younger people.
Currently 85.2 per cent of 20 to 24-year-olds are fully vaccinated, and 87 per cent of 25 to 29-year-olds.
For context, this level of vaccination coverage is lower than other age groups in Australia, but still far higher than most countries in the world.
And while official data has not been gathered, high levels of vaccine hesitancy have also been reported in pregnant women.
There are concerns of up to a third of pregnant women could be unvaccinated.
And last, there are those who hold "anti-vax" views.
Julie Leask from the University of Sydney Institute for Infectious Diseases is a leading authority on why people choose not to get vaccinated and she says it's not useful to label or stigmatise vaccine rejection.
"It does a lot more harm than good. The anti-vax activists are a tiny but vocal minority. Those who remain unvaccinated are strong in their views but diverse in their reasoning."
