CLEVELAND, Ohio – The second dose of Pfizer’s COVID-19 vaccine must be postponed to stretch supplies, as one injection protects almost as well as two against severe cases, two Canadian researchers wrote in a letter published in the New England Journal of Medicine .
Pfizer’s response to the researchers’ letter, also published in The New England Journal of Medicine, said that “alternative dosing regimens” for its vaccine have not yet been adequately evaluated.
“The decision to implement alternative dosing schedules rests with the health authorities,” said Pfizer. “However, we at Pfizer believe that it is critical for health authorities to conduct surveillance on alternative dosing schemes implemented to ensure that vaccines provide the maximum possible protection.
Researchers Danuta Skowronski and Gaston De Serres analyzed the data submitted by Pfizer to the Food and Drug Administration and determined that the first dose of the vaccine has an efficacy rate of approximately 92.6%.
The Pfizer vaccine when administered in two doses 21 days apart has an efficacy of 94.8% against COVID-19 after two doses.
Dr. Anthony Fauci, the leading infectious disease specialist in the United States, recently said on NBC’s “Meet the Press” program that he disagreed with experts who asked for a second dose to be postponed. More research is needed to measure the level of long-term protection that people get with just one injection, he said.
“The amount of time it will take, the amount of people you would have to put in the study – by then, we will be in the arena of having enough, having enough vaccines to circulate anyway,” said Fauci.
Given the relatively small increase in the rate of effectiveness between the first and second doses, the authors argued in the letter that “the benefits derived from a scarce supply of vaccine could be maximized by postponing second doses until all members of the priority group are offered at least one dose. ”
So far, health experts have urged the public to obtain two doses of the Pfizer and Moderna vaccines for maximum protection against COVID-19.
The letter advocating a single injection comes as public health experts debate whether to delay second doses of COVID-19 vaccines so that more people in the high-risk categories can receive their first injection sooner.
Canadian researchers recognized that while “there may be uncertainty about the duration of protection with a single dose”, the second dose weeks after the first “provides little additional benefit in the short term, while high-risk people who could have received a first dose dose with that vaccine supply are left completely unprotected. ”
The first dose of Pfizer or Moderna is “quite impressive,” said Dr. Bruce Vanderhoff, medical director of the Ohio Department of Health, during Governor Mike DeWine’s COVID-19 briefing.
“They generate very substantial levels of antibodies and demonstrate a very significant ability to prevent people from developing COVID disease,” said Vanderhoff of the vaccines.
Can someone get COVID-19 between the two doses. But the second dose does more than just raise antibody levels. It activates the adaptive immune system. It is a largely cellular part of the immune system.
“This is important, because it is what allows the vaccine to last,” he said.
And it activates what he called “agile” immunity, which helps to protect against coronavirus variants.
“Both [doses] are needed, ”said Vanderhoff. “The first is very good. But you are not done with the first. “
A growing number of countries are considering postponing the second dose of COVID-19 vaccines in order to maximize the number of people who can get their first injection.
Health experts in France are debating whether to give people who have recovered from COVID-19 just one dose of the vaccine instead of two in order to release doses to others.
The World Health Organization said in January that in “exceptional circumstances”, the second dose of the Pfizer vaccine can be administered up to six weeks after the first.
The United States Center for Disease Control and Prevention recommends receiving the second dose of the Pfizer vaccine as close to the schedule as possible. The vaccines were approved based on clinical trial data, and those clinical trials did not consider the effects of a significant delay, health experts said.