"Some people may be really motivated to have higher levels of immunity quicker … they might have family members who are particularly vulnerable and just want to make sure they have protection." What about mixing and matching vaccines? But, she added, there was also an argument for having more flexibility in our dosing regime. "If you deferred the due date for the second dose until a time when more Pfizer vaccines were available, what you buy is the level of not perfect, but very good, protection for a much larger percentage of the population."ĭr Quinn said that because Australia doesn't have significant levels of community transmission, there was rationale behind sticking to the recommended vaccine intervals in order to achieve maximum individual protection. "The data shows that at least one dose of protection is actually excellent," he said. Research has shown that just one dose of Pfizer offers up to 85 per cent protection. That would mean available supplies could be used to give more people a first dose, rather than giving people who are already partially-protected a second dose. ( Getty Images: Lisa Maree Williams/Stringer) Stretching out the time between Pfizer doses could speed up the roll-out. Professor Nolan said another option to get more of the population at least partially vaccinated was to consider extending the interval between the first and second doses of Pfizer. "The argument was being made early that there's no race, we don't have to hurry. "The best counter to that would be to get as much of the population protected with vaccines as quickly as possible," he said. Professor Nolan said cutting down the time between AstraZeneca doses could help more people get vaccinated sooner, particularly with the threat of outbreaks growing during winter. In Australia, just seven per cent of the adult population has been fully vaccinated against COVID-19. "It's understanding those trade offs and understanding what's best for that particular population." Should Australia change its guidance? "It makes good sense to try and build people's immunity up to a decent level quicker, and perhaps accept a slightly lower level of antibody responses," Dr Quinn said. If building the highest protection possible in every individual is top priority, then waiting longer to receive the second dose is the better option, Dr Quinn said.īut in places where there are high levels of community transmission, such as the UK, fast-tracking second doses may be a better option. "The Delta variant has changed the environment for vaccines in the UK … We now know that two doses of vaccine are very much better than one dose for protection against infection with the Delta variant," UK deputy chief medical officer Jonathan Van-Tam said.Ĭlinical epidemiologist Terry Nolan said the emergence of the Delta variant and the sheer number of COVID-19 cases in the UK meant they urgently needed to get as many people fully vaccinated as possible. Why have some countries reduced wait times?Īs the highly contagious Delta variant takes hold in many parts of the world, including the UK, health authorities have decided to reduce the interval between AstraZeneca vaccines from 12 weeks to eight weeks for people aged 40 and above. Receiving a second dose 12 weeks or more after the first can kick this protection up to around 81 per cent.īut this efficacy dropped to around 55 per cent if the second jab was given less than six weeks after the first, the study found. This is in line with research that has shown that a 12-week wait between doses provides optimal protection against COVID-19.Ī study published earlier this year in The Lancet found that a single dose of AstraZeneca is 76 per cent effective in the first 90 days. Read our full coverage of the coronavirus pandemic The Australian Technical Advisory Group on Immunisation (ATAGI) currently recommends people who have received their first dose of the AstraZeneca vaccine should wait 12 weeks to get their second, with a minimum wait of four weeks. Research shows a wait of 12 weeks provides optimal protection against COVID.
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