The Food and Drug Administration rejected proposals floated by other federal health officials for cutting COVID-19 vaccine doses in half to cover twice as many people will provide.
“We know that some of these discussions about changing the dosing schedule … are based on a belief that changing the dose or dosing schedule can help get more vaccine to the public faster,” FDA Commissioner Stephen Hahn said in a statement Monday evening. “However, making such changes that are not supported by adequate scientific evidence may ultimately be counterproductive to public health.”
Federal health officials leading the vaccine rollout have been debating the idea of giving out as many first doses of two-dose vaccines as possible rather than waiting to give patients both doses. Some say the proposal could accelerate the immunization process and end the pandemic sooner, but the FDA dismissed those arguments.
“Until vaccine manufacturers have data and science supporting a change, we continue to strongly recommend that health care providers follow the FDA-authorized dosing schedule for each COVID-19 vaccine,” Hahn said in the statement, which was issued jointly with Center for Biologics Evaluation and Research Director Peter Marks.
The Moderna and Pfizer/BioNTech vaccines have been shown to be most effective when the booster is administered 28 days and 21 days after the first, respectively. Evidence that single doses afford people the same protection, the FDA said, “is commonly being misinterpreted.” Those who received only one dose of either vaccine in clinical trials were surveilled for only a short period of time compared with those who received both shots.
Officials leading the vaccine development initiative Operation Warp Speed have been criticized for the slower-than-desired vaccine rollout, a massive undertaking that aims to innoculate roughly 100 million people by March.
Moncef Slaoui, chief of Operation Warp Speed, said on Sunday that the Trump administration is asking vaccine maker Moderna about halving the doses as a means of shoring up limited supplies and giving twice as many people access to the shots as quickly as possible.
“We know that, for the Moderna vaccine, giving half of the dose to people between the ages of 18 and 55, two doses [at] half the dose … we know it induces identical immune response” to the currently authorized two-dose regimen, Slaoui said.
The vaccine trials did not include tests for efficacy of single doses. Moderna’s Phase 3 clinical trial data showed that a single dose of the vaccine was slightly over 80% effective at generating a robust immune response, compared with a 94% efficacy rate with a two-dose regimen. Still, the trial results show that the short period in which researchers monitored single-dose recipients limited their ability to determine that one shot was as effective as two.
The federal government struck a deal with Moderna to procure 200 million doses of the vaccine, enough to immunize 100 million people. But the vaccine rollout process has gone slower than desired, with about 4.6 million people having been given shots since Dec. 14, far short of the goal public health officials set last month to give at least 20 million people their first shots before the end of the yea
A Moderna spokesperson told the Washington Examiner earlier on Monday that clinical trials were designed to record efficacy after two doses, not one, adding that they could not comment on potential regulatory discussions with the FDA.
Pfizer, meanwhile, said last week the emergency use authorization granted by the Food and Drug Administration last month “was designed to evaluate the vaccine’s safety and efficacy following a 2-dose schedule. … There are no data to demonstrate that protection after the first dose is sustained after 21 days.” Indeed, the New England Journal of Medicine reported on Dec. 30 that “some degree of prevention may be afforded after the first dose” but additional study is needed.
Some governments have already employed the single-dose strategy, with the goal of administering shots to as many people as possible. The United Kingdom announced last week that it would extend the interval between doses of the Pfizer or AstraZeneca vaccine up to 12 weeks in order to provide at least partial protection to a wider swath of the population.
The Quebec Health Department will also make all of the doses available at once rather than reserve half to provide boosters to those who received the first shot.
Yet, Dr. Anthony Fauci, the U.S. government’s top infectious disease expert, warned against Britain’s move on Sunday, saying the government shouldn’t deviate from the authorized dosing regimen.
“If we do it efficiently the way we’ve planned, it’s much better than trying to stretch it out and not having a scientific basis of knowing what happens if you wait … 50 or 70 [days],” Fauci said. “We don’t know whether or not that’s going to be good enough. We know what the science tells us. … Let’s do it the way the clinical trials have instructed us to do it.”
Surgeon General Jerome Adams, meanwhile, referred back to Fauci when asked about the merit of spacing out doses, saying Monday that “we need to let science lead the way.”
“We’re going to make sure we get as much vaccine to as many people as possible and getting it into arms,” he said. “Tony Fauci has said clearly that he does not think it’s appropriate for us to eliminate the second dose or push it back at this point, but we are looking again at halving the dose.”
Nongovernment public health experts are also making a case for delaying the second doses of each vaccine. Dr. Scott Gottlieb, a Pfizer board member who served as FDA Commissioner from 2017 until April 2019, said Monday that cutting the doses of Moderna’s vaccine in half would create “significantly more doses than just the 200 million that we talk about that’s going to be available the first half of the year.”
