Experts flag issue with vaccine rollout
Australia must change its COVID-19 vaccination strategy as AstraZeneca does not provide enough protection for the community, experts have warned.
In an opinion piece on Policy Forum, economist and modeller Professor Quentin Grafton of Australian National University, along with other experts including epidemiologist and biostatistician Dr Zoë Hyde of the University of Western Australia, put forward four changes they believe are necessary for Australia's vaccination program.
"With the emergence of more transmissible new variants, Australia's current COVID-19 vaccination strategy doesn't make sense from either a public health or an economic perspective," they write.
"It must change or Australia risks a future epidemic and/or very large costs from lockdowns when its international border reopens."
They believe Australia needs to do four things.
1. Strengthen the country's quarantine system by acting on the latest evidence of the role of airborne transmission in quarantine breaches;
2. Aim for herd immunity by using vaccines with the highest possible efficacy, such as Moderna, Novavax, and Pfizer, as they provide security against even concerning new variants of the virus;
3. Not relax international border restrictions until everyone has had the opportunity to be vaccinated; and
4. Establish mass vaccination hubs in major centres to maximise the number of people who can be vaccinated each day, as Victoria is doing.
Concerns over AstraZeneca
The experts are critical of the AstraZeneca vaccine, which Australia is relying on to vaccinate people over 50 years old.
"Herd immunity is the only way to eliminate community transmission for good and to avoid costly lockdowns," they write.
"This can be achieved with a Pfizer or Pfizer-Novavax vaccination strategy, but not with the country's current approach because it will be impossible to achieve herd immunity against several of the world's most concerning variants using AstraZeneca."
It notes that "real world experience" shows the Pfizer vaccine is 75 per cent effective against infections caused by the South African (B. 1.351) variant and 90 per cent effective against the UK (B.1.1.7) variant.
The AstraZeneca vaccine only has 10 per cent efficacy against the South African variant, although it's probably still reasonably effective against severe disease.
The authors say variants threaten "both young and old" because younger people are more likely to be hospitalised.
"In other words, the risk for a 20 to 39-year-old is now similar to the risk previously faced by a 40 to 59-year-old," they note.
"Variants also markedly increase the likelihood of dying from COVID-19; the United Kingdom variant raises this risk by 64 per cent."
The authors, which also include Professor of Biosecurity and Environmental Economics, Tom Kompas at the University of Melbourne and mathematician and modeller Dr John Parslow, say it's also "inequitable" to impose AstraZeneca on those who are 50 years and older.
"It knowingly gives older people, who face a higher risk of severe disease and death from COVID-19, a less effective vaccine," they argue.
"It also runs the risk of creating a situation where the South African variant could spread in Australia's older population should border controls be relaxed or if an outbreak should occur.
"Seychelles, which has fully vaccinated the highest proportion of its population than any country at 61 per cent - 40 per cent of the total population with a version of the AstraZeneca vaccine made under license in India - is now facing a surge of cases in which the South African variant appears to be playing a role."
They argue that data around AstraZeneca's effectiveness at preventing severe disease or death is also not as clear as some have suggested.
"It's been claimed the vaccines in Australia's portfolio are 100 per cent effective at preventing severe illness and death, but that's not supported by science," they write.
"There were too few severe cases in the AstraZeneca trials to accurately assess this endpoint, and the estimated efficacy lies somewhere between 72 and 100 per cent for severe illness.
"In contrast, real world experience from Israel has shown the Pfizer vaccine is 97.5 per cent effective against severe disease, with a confidence interval of 97.1 to 97.8 per cent."
The risk of blood clots
AstraZeneca also carries a risk of blood clots and the authors note that the European Medicines Agency has doubled its estimate of the risk of blood clots for older people since the Australian Technical Advisory Group on Immunisation (ATAGI) carried out its original analysis of the issue.
The authors believe this would have changed ATAGI's risk analysis in the case of another outbreak in Australia (equivalent to its first wave in which there were 7000 cases and 100 deaths).
"Critically, if ATAGI had used the revised and higher estimates of blood clot risks … it would have also recommended against AstraZeneca for those aged between 50 and 60," they write.
The authors say the Australian Government must reassure the public that the use of the AstraZeneca vaccine among those over 50 years old is necessary, and is not just being imposed to allow earlier reopening of international borders.
While a three to six month delay in reopening the international border could cost the economy $6 billion to $12 billion, it could be worth it so everyone can be vaccinated with Pfizer or Novavax rather than AstraZeneca, they say.
They point out the cost is much less than the cost of a prolonged lockdown if a major outbreak occurred, or if more frequent short lockdowns were necessary following the international border reopening.
"Australia's vaccination strategy must change as the facts change," they argue.
"Crucially, an AstraZeneca only vaccination strategy for those aged 50 and over will not provide the level of protection necessary to safely relax border controls, nor will it deliver herd immunity," they said.
"The country won't be truly safe until we've reached herd immunity. Reaching this threshold ensures an outbreak won't spread rapidly in the community and lead to an epidemic.
"It also protects the millions of Australians who can't be vaccinated due to medical reasons, or aren't currently eligible for vaccination, such as children and adolescents."
However, Deakin University epidemiologist Professor Catherine Bennett doesn't agree, and believes "the vaccine you have in your arm is better than a potential one down the track".
"AstraZeneca has fantastic efficacy on most strains," she told news.com.au.
"To not give it when we've got it, is problematic to me."
Prof Bennett said it was better to use the vaccine that was available as eventually they would all be tweaked and improved to give better coverage.
Waiting for Pfizer would push the vaccination program "well into next year" and Australia could struggle as the rest of the world opened up using vaccinations such as Pfizer or AstraZeneca.
"I don't think cutting back on our vaccination strategy now makes public sense," she said.
"We need to have some level of population protection and then we can build on that."
Originally published as Experts flag issue with vaccine rollout