Share article:
Share article:

Vaccines: AstraZeneca and Pfizer lose effect with time

© Belga

Two of the main vaccines against Covid-19 lose their effect against the virus as time goes on, according to a new study by scientists at Oxford University.

Caveat: The study has yet to be published in an official medical journal, and should therefore be considered unconfirmed foe the time being.

The study looked at 2.6 million nose- and throat-swabs taken from more than 384,500 volunteers in the period from December 2020 and mid-May this year, as well as 811,600 test results from 358,983 adults between mid-May and 1 August 2020.

The results showed that the AstraZeneca vaccine – which was developed in conjunction with Oxford University – had fallen in effectiveness from 80% protection after two weeks to 61% after 90 days.

The Pfizer vaccine, developed with BioNTech and manufactured in Puurs in Antwerp province, dropped from 95% protection after seven days to 75%, 90 days after a second vaccination.

An important factor in the difference is thought to be the arrival of new variants of the SARS-CoV-2 virus – first the alpha or British variant in the earlier period of the test, and later the delta or Indian variant in the later stage.

Vaccines are constantly being adjusted and refined to cope with the arrival of new variants of a virus – as happens annually when you have to have your flu shot renewed.

But a vaccine that has already been administered cannot be adjusted to take account of a new variant that comes along at such a rapid pace as has been occurring with the Covid variants.

“We quickly see a reduction in effectiveness, but it is not so dramatic that we need to be very concerned about this,” Dutch epidemiologist Koen Pouwels, who participated in the study in Oxford, told the VRT.

“After three months, the protection is still a lot better than what the World Health Organization (WHO) initially proposed.”

“Both of these vaccines, at two doses, are still doing really well against Delta,” said Sarah Walker, an Oxford professor of medical statistics and chief investigator for the survey. “When you start very, very high, you have a long way to go.”

Latest news

Over 1,000 Covid-19 hospitalisations for first time since early June
The number of patients hospitalised in Belgium as a result of the coronavirus has again exceeded 1,000, climbing to 1,032, according to figures ...
Experts call for more widespread use of masks as figures rise
As coronavirus figures continue to rise, Belgian Prime Minister Alexander De Croo has suggested that people return to wearing masks when indoors with ...
Belgium wants to recover €420 million in wrongfully paid out coronavirus aid
The Belgian State intends to recover €420 million of unduly paid Covid-19 aid, La Libre Belgique reported on Thursday. The electronic Council of ...
Why the fight for transgender rights is polarising Europe 
Year after year, Samuel De Schepper would ask Santa Claus to bring him a penis for Christmas. Born female and attending an all girl’s Catholic ...
New offshore wind farm officially opened
Despite being operational since the end of 2020, the SeaMade offshore wind farm was officially inaugurated on Wednesday by Prime Minister Alexander ...
Contact tracers have no time for calls, only texts, amid rising cases
Contract tracers will no longer make phone calls to the high-risk contacts of people who test positive for the coronavirus beginning from Wednesday, ...
Belgium holds on to top spot in FIFA rankings despite recent losses
Once again, Belgium's Red Devils have held onto their position at the top of the world football rankings, according to an update released by the ...
Proximus pushes for high-speed internet in Brussels and Wallonia
Fifteen municipalities in Wallonia should soon have access to high-speed internet through the rollout of fibre optics in the region, telecoms giant ...
Why Belgium is regulating sex work
After decades of confusing rules and hypocritical policy, Belgium is finally regulating sex work by removing prostitution from the criminal law. ...
World’s largest chocolate warehouse opens in Flanders
On Thursday, Barry Callebaut – the largest global chocolate processor and manufacturer – opened the world's largest chocolate warehouse in Lokeren, ...
Belgium in Brief: Equal Opportunity To Dance
There's a phrase where I'm from, more often said in jest nowadays, but it came to my mind this morning: "Ye dancin'?" (Are you dancing?), one ...
Farmer discovers cocaine in banana boxes bought in Brussels
A Flemish farmer who purchased boxes of bananas at the market in Brussels on Tuesday came home to discover large amounts of cocaine packed among the ...