Covid vaccinee Petra Moinar prepares syringes with the AstraZeneca vaccine before it is administered on March 8, 2021 at the Battersea Arts Center in London, England.
Chris J. Ratcliffe | Getty Images News | Getty Images
LONDON – Protection against the coronavirus is declining in those who have received both AstraZeneca and Pfizer vaccines, a new UK study found.
An analysis by the UK’s ZOE Covid app study of over 400,000 people who had both vaccinations of the Pfizer BioNTech vaccine showed that it was 88% effective against coronavirus one month after receiving both vaccinations. However, its effectiveness dropped to 74% five or six months after receiving both doses of the Pfizer vaccine.
In the same study, an analysis of over 700,000 people who received both doses of the Oxford AstraZeneca vaccine showed that its effectiveness decreased from 77% after one month to 67% after four to five months.
The data was collected after May 26, when the Delta variant became the dominant strain, said Tim Spector, who runs the ongoing ZOE Covid app study.
Spector, a professor of genetic epidemiology at King’s College London, presented this latest data during a webinar Tuesday and said the results showed, over the months, a “reduced benefit” from the protection afforded by these two vaccines.
Nearly 42 million people in the UK, 77% of the population over the age of 16, have received two doses of a Covid vaccine, according to government figures last updated Tuesday. The daily data showed that 30,838 Covid-19 infections were registered on Tuesday, while 174 people had died within 28 days of testing positive for the virus.
Alexander Hammers, professor of imaging and neuroscience at King’s College London, said in the webinar that it is already known from other coronaviruses that immunity to the disease does not usually last for life.
“So we knew there was going to be an equalization and the way I see it, the equalization is actually a little slower than I expected,” he said.
And although the data showed the vaccines to be “declining” in effectiveness over time, Hammers said people were “probably still at least 50% protected.”
“Remember, when the vaccines were first developed, it was hoped they would be 60-70% efficacy and everyone was pleasantly surprised that they got well over 80%, sometimes well over 90,” he added.
Even so, Spector said he was still “a bit concerned” about coronavirus data from Israel, which had one of the fastest vaccination programs in the world and was ahead of the UK
He noted that even though much of its population has been vaccinated, Israel has seen increasing hospitalizations and deaths from the coronavirus.
Data published by Israel in July showed that the Pfizer vaccine was only 16% effective against symptomatic infections in people who received two doses in January.
However, comparing the results is difficult given the differences in the type of vaccination programs in different countries as well as the different study dates, age groups and Covid test regimes.
Two U.S. studies released Tuesday by the Centers for Disease Control and Prevention showed declining immunity to Covid in fully vaccinated people, one of whom focused on frontline workers.
The webinar panelists of the ZOE Covid study also discussed whether the declining effectiveness of the vaccines would increase the need for Covid booster vaccinations in the future. Spector pointed out that Israel has already started giving booster vaccinations.
Anna Goodman, an infectious disease and general medicine consultant with the London NHS Endowment Fund Guy’s and St If Everyone in the World Is Vaccinated. ”
– CNBC’s Holly Ellyatt contributed to this article.