Two Canada-based researchers have suggested delaying the second dose of the Pfizer/BioNTech COVID-19 vaccine in a bid to protect more people within a shorter timeframe.
In a letter published in the New England Journal of Medicine (NEJM), the researchers, Danuta Skowronski and Gaston De Serres, made their case for delaying the second dose of the Pfizer/BioNTech vaccine.
Using documents submitted to the US Food and Drug Administration (FDA), the researchers derived the vaccine’s efficacy beginning from two weeks after the first dose to before the second dose is administered.
They found that, even before receiving the second dose, the Pfizer/BioNTech vaccine – also known as BNT162b2 – was ‘highly efficacious’ with a vaccine efficacy of 92.6%.
The researchers added that there may be some uncertainty around the duration of this response following a single dose.
However, they maintained that the administration of a second dose within a month of the first dose provides ‘little’ additional benefit in the short-term.
These extra doses, they suggest, could be instead used to protect more individuals who are at the highest risk of developing complications from COVID-19.
“With such a highly protective first dose, the benefits derived from a scarce supply of vaccine could be maximised by deferring second doses until all priority group members are offered at least one dose,” wrote Skowronski and De Serres.
In the UK, a 12-week interval between doses of the Pfizer/BioNTech vaccine has been recommended.
In a letter regarding the rationale behind this dosing schedule, the UK’s chief medical officers said: “The second vaccine dose is likely to be very important for duration of protection and, at an appropriate dose interval, may further increase vaccine efficacy.
“In the short term, the additional increase of vaccine efficacy from the second dose is likely to be modest.”
BioNTech’s chief executive Ugur Sahin told Sky News that the second dose of BNT162b2 should be given no more than six weeks after the first dose.
“As a scientist, I wouldn’t mind if the second dose of the vaccine is given three weeks, four weeks, maybe five weeks, even up to six weeks might still be okay,” said Sahin.
“But I wouldn’t delay that further. As a scientist I believe that it is not good to go longer than six weeks,” he added.
Regarding the UK’s decision to push the second dose to 12 weeks following the first, Sahin also said: “The pros are very clear – by immunising more people we could get the benefit to more people. But we need to be also aware that we will only get partial benefit to more people.
“So at the end of the day it is a risk-benefit assessment from governmental bodies whether the benefit by reaching more people is sacrificed by giving less protection to the vaccinated people.”