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Protection against COVID-19 reduces over time in fully vaccinated, according to new real-world study

The Zoe COVID-19 Study shows protection could fall by up to 14%

Data from a new real-world study has found that protection against COVID-19 is ‘waning’ in double-vaccinated individuals.

The Zoe COVID-19 Study app analysed data on positive COVID-19 PCR test results processed between May and July 2021, taken by more than one million people who had received two doses of either the Pfizer/BioNTech or AstraZeneca (AZ) vaccine.

The researchers, led by Professor Tim Spector, lead investigator on the Zoe COVID-19 Study app behind the research, found that following two doses of the Pfizer/BioNTech jab, protection fell from 88% at one month to 74% at five to six months.

For those vaccinated with the AZ vaccine, protection similarly dropped – within a slightly shorter timeframe of four to five months – from 77% to 67%.

"Waning protection is to be expected and is not a reason to not get vaccinated. Vaccines still provide high levels of protection for the majority of the population, especially against the Delta variant, so we still need as many people as possible to get fully vaccinated,” said Spector.

He continued to say that the findings could explain the recent breakthrough infections reported by some fully vaccinated people.

The UK is awaiting JCVI advice and results from a government-funded trial investigating the efficacy of a third dose for immunocompromised people before making an announcement of a potential roll-out of a third jab – initially expected to start in September.

Speaking about the need for a booster jab, Spector said: "Many people may not need them. Many people may have had a natural booster because they've already had a natural COVID-19 infection, so will effectively have had three vaccines.”

The results follow a similar study published last week by the Office for National Statistics and the Oxford Vaccine Group. The results show that, while both vaccines were effective against the Delta variant, protection wanes over time. While Pfizer/BioNTech’s Comirnaty was 92% effective against high viral load 14 days after the second dose, it fell to 78% after 90 days. AZ’s Vaxzevria also saw a drop, from 69% effective against high viral load after 14 days to 61% after 90 days.

Last week also saw US health leaders greenlight COVID-19 booster shots in light of the “very clear” evidence that protection declines over time. In the US, booster shots will potentially be available in late September, subject to FDA and CDC recommendations.

Article by
Bryony Andrews

25th August 2021

From: Research, Healthcare



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