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CLEVELAND, Ohio – The second dose of Pfizer’s COVID-19 vaccine should be delayed in order to stretch stocks, since 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 “alternative dosing schedules” for its vaccine have yet to be properly evaluated.
“The decision to implement alternative dosing regimens rests with the health authorities,” said Pfizer. “However, at Pfizer, we believe it is essential that health authorities conduct oversight over the alternative dosing regimens being implemented to ensure that the vaccines provide the maximum protection possible.”
Researchers Danuta Skowronski and Gaston De Serres analyzed data submitted by Pfizer to the Food and Drug Administration and determined that the first dose of the vaccine had an effectiveness rate of around 92.6%.
The Pfizer vaccine, given in two doses 21 days apart, is 94.8% effective against COVID-19 after two doses.
Dr Anthony Fauci, the leading infectious disease specialist in the United States, recently told NBC’s “Meet the Press” that he disagreed with experts calling for a delayed second dose. More research is needed to measure the level of long-term protection people get all at once, he said.
“How long it takes, how many people you need to put in the study – by then we’ll be in the arena already to have enough, to have enough vaccines to go around anyway. “said Fauci.
Given the relatively small increase in the efficacy rate between the first and second dose, the authors argued in the letter that “the benefits derived from a limited vaccine supply could be maximized by delaying the second doses until. ” that all members of the priority group are offered at least one dose. “
So far, health experts have urged the public to obtain both doses of the Pfizer and Moderna vaccines for maximum protection against COVID-19.
The letter advocating a single vaccine comes as public health experts debate whether to delay second doses of COVID-19 vaccines so that more people in high-risk categories can receive their first vaccine sooner.
Canadian researchers recognized that while “there may be uncertainty as to how long protection will last with a single dose,” the second dose a few weeks after the first “offers little additional short-term benefit, while High-risk people who could have received a first dose with this vaccine supply are left completely unprotected. “
The first dose of Pfizer or Moderna is “pretty impressive,” Dr. Bruce Vanderhoff, chief medical officer of the Ohio Department of Health, said during Gov. Mike DeWine’s COVID-19 briefing Thursday.
“They generate very high levels of antibodies and demonstrate a pretty big ability to prevent people from developing COVID disease,” Vanderhoff said of vaccines.
Someone could catch COVID-19 in between doses. But the second dose does more than just increase antibody levels. It triggers the adaptive immune system. It is a largely cellular part of the immune system.
“This is important, because it is what allows the sustainability of the vaccine,” he said.
And it triggers what he called “agile” immunity, which helps protect against variants of the coronavirus.
“Both [doses] are needed, ”Vanderhoff said. “The first one is very good. But you haven’t finished with the first one.
A growing number of countries are considering delaying second doses of COVID-19 vaccines, to maximize the number of people who can receive their first vaccine.
Health experts in France are wondering whether to give people who have recovered from COVID-19 a single dose of the vaccine instead of two, in order to free up doses for others.
The World Health Organization said in January that under “exceptional circumstances” the second dose of Pfizer vaccine can be given up to six weeks after the first.
The US Centers for Disease Control and Prevention recommends getting the second dose of Pfizer vaccine as close to schedule as possible. The vaccines were approved based on clinical trial data, and those clinical trials did not take into account the effects of a significant delay, health experts said.
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