Health authorities are urging Australians who have not yet received their COVID-19 booster vaccination to roll up their sleeves, with coronavirus cases expected to rise in the coming weeks.
The increasingly dominant Omicron BA.2 subvariant, thought to be more transferable than its widely circulating cousin BA.1, has experts predict that COVID-19 cases could jump significantly.
On Thursday, NSW looked at more than 20,000 cases alone.
“People need to understand that while the community has been sleeping on the virus, the virus has not been sleeping on the community,” NSW Health Minister Brad Hazzard said last week.
“The virus is still out there and it can cause harm if we do not go and get our boosters quickly.”
Since the federal booster program began last November, the inclusion of third doses has been declining.
Department of Health data show that 66 per cent of Australians over 16 have received more than two doses of a COVID-19 vaccine.
“This is compared to 95 per cent of the population who have two doses,” said epidemiologist and biostatistician Adrian Esterman of the University of South Australia.
“Also [booster rates] are way, way down. “
Boosters improve protection, especially in the elderly
While booster vaccines are not mandatory in most cases, they are recommended for anyone 16 years of age and older to maintain immunity to COVID-19.
This is because COVID-19 vaccines are constantly losing their effectiveness over time, especially against infection and symptomatic disease.
“With two doses, you still get protection against serious illness, but you have almost zero protection against infection with Omicron,” said Professor Esterman.
Infectious Diseases Doctor Peter Collignon said the benefit of booster vaccinations was greatest in the elderly, who are at the highest risk of serious complications of COVID-19.
According to data obtained by Nine Newspapers, around 900,000 Australians aged 60 and over have a booster.
“Vaccines significantly reduce the risks … three doses, if you are older, will give you about a 20-fold reduction in your chances of dying,” said Professor Collignon of the Australian National University.
He said Australians should only look at the situation unfolding in Hong Kong, where cases and deaths have risen sharply in the elderly to see the impact of vaccinations.
“Hong Kong had a reasonable intake of COVID vaccines at 30- and 40-year-olds, but in their elderly they had poor intake – about 30 percent, even just from two doses,” he said.
“They are now seeing some of the highest death rates in the world.”
Professor Collignon said Australia should count on 95 per cent booster coverage for people over the age of 70, although it has been suggested that the same should apply to people over 50.
What about the disappearance of immunity? And the BA.2 variant?
The efficacy of COVID-19 boosters, like those of the primary vaccine doses, seems to diminish over time, especially against infection.
“The third dose really gives you good protection against both infection and serious illness, but the protection against infection is basic in a couple of months,” said Professor Esterman.
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Against more serious illness, a report by the CDC in February published that booster effectiveness has decreased, but less significantly.
Data show that protection against emergency department visits increased from 87 percent in the first two months after a third dose to 66 percent after four months.
The vaccination efficiency against hospitalization went up from 91 per cent in the two months following a third dose to 78 per cent in the fourth month.
One limitation of these data is that they were not degraded by age, and the researchers were unable to distinguish between a booster dose or a third dose given to an immunocompromised person (as part of their primary series). This means that booster shots seem less effective than they actually are.
Professor Collignon said that ongoing studies were needed to measure the length of the third dose, and that it was important to look beyond just the antibodies that trigger it.
“Just looking at antibody levels is not necessarily correlated with how good protection is, because white cells and T cells are probably more important in preventing people from getting seriously ill … and that’s a lot harder to measure. , “he said.
As to whether the BA.2 subvariant is better able to avoid our immune system (excused by vaccinations or infection), early research says that this is not the case.
Preliminary UK data show that the effectiveness of vaccination against symptomatic disease is similar to BA.1 and BA.2, and according to the World Health Organization, initial studies show that infection with BA.1 “provides strong protection against new infection with BA.2” bitt.
Unpack Low Booster Recording
Infectious Disease Social scientist Holly Seale said to strengthen the slow uptake of third doses in some groups, it would be important to understand why people do not move forward.
She said a “shift in perception” around COVID-19 risks, coupled with a decline in cases and reduced public health measures, means some people may feel less compelled to seek vaccination.
“People may think,‘ What is the rationale for getting a booster if anyone [they know] seems to come through COVID OK? said Dr. Seale.
State-based data show that booster rates are as low as 40 percent among some younger cohorts.
Professor Esterman said it was understandable that young people were slower to seek third doses because they had a much lower risk of complications from COVID-19.
But he said the risk of serious illness was not zero, and that there was also the possibility of long-term COVIDs being considered.
“To say that I do not care if I get infected is a bit risky,” he said.
Dr Seale added that booster rates may be low in some cases because “we have a large number of people receiving COVID-19”, and therefore delaying vaccination.
But she added that an increase in public health campaigns could help address low incomes, especially in areas where limited community education or outreach means the message about boosters is not getting through.
“We must continue to refresh these messages,” she said.
Will some of us need four doses?
Earlier this week, Pfizer announced that it was seeking emergency authorization from the U.S. Food and Drug Administration for a second COVID-19 booster for adults 65 and older.
Some countries have already moved to recommend a second booster for vulnerable groups, including people with immunodeficiency, people over 70 (or in Israel, over 60), health care providers, and elderly residents and staff.
In Australia, four doses are currently only recommended for immunocompromised individuals who tend to produce a less robust response to vaccines.
But last week, Federal Health Minister Greg Hunt said the government’s vaccination advisory body, ATAGI, had also considered recommending a fourth dose for Australians over 65.
Professor Esterman said he expects the fourth-dose claim to be extended, especially before winter, when both COVID and flu infections are predicted to go up.
“What happens is a lot of elderly and vulnerable people who got their booster dose in November or December now have little protection against infection, and really need a fourth dose – only a third,” he said.
“People who are severely immunocompromised are a very small, select group of people.
“There is a much broader group of people who are elderly, frail, or who have underground health conditions that put them at risk.”
Professor Collignon said that four doses could prove necessary for the elderly, but that there was still not enough data to suggest that they were needed – or possibly profitable – for the general population.
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