Two top officials with the Food and Drug Administration (FDA) have announced they oppose a plan to cut the dosage of a COVID-19 vaccine in half, saying the move is “premature.”
On Sunday, Moncef Slaoui, chief scientific adviser of Operation Warp Speed, a vaccine program established by President Donald Trump, said half a dose of the Moderna vaccine is just as effective as a full dose. “We know that for the Moderna vaccine, giving half of the dose to people between the ages of 18 and 55, two doses, half the dose, which means exactly achieving the objective of immunizing double the number of people with the doses we have,” Slaoui said on CBS’ “Face the Nation.”
“We know it induces identical immune response” to the full dose, he added. With vaccines in short supply, Slaoui suggested cutting the vaccine doses in half was “a more responsible approach that would be based on facts and data.”
But FDA Commissioner Dr. Stephen Hahn and Dr. Peter Marks, director of the Center for Biologics Evaluation and Research, the agency’s vaccine division, said Monday that anyone getting either the Moderna or Pfizer vaccine should take two full doses.
“We have been following the discussions and news reports about reducing the number of doses, extending the length of time between doses, changing the dose (half-dose), or mixing and matching vaccines in order to immunize more people against COVID-19,” the pair said in a statement on Monday.
“These are all reasonable questions to consider and evaluate in clinical trials. However, at this time, suggesting changes to the FDA-authorized dosing or schedules of these vaccines is premature and not rooted solidly in the available evidence. Without appropriate data supporting such changes in vaccine administration, we run a significant risk of placing public health at risk, undermining the historic vaccination efforts to protect the population from COVID-19,” they added
“The available data continue to support the use of two specified doses of each authorized vaccine at specified intervals. For the Pfizer-BioNTech COVID-19 vaccine, the interval is 21 days between the first and second dose. And for the Moderna COVID-19 vaccine, the interval is 28 days between the first and second dose,” the two doctors wrote.
“Using a single dose regimen and/or administering less than the dose studied in the clinical trials without understanding the nature of the depth and duration of protection that it provides is concerning, as there is some indication that the depth of the immune response is associated with the duration of protection provided. If people do not truly know how protective a vaccine is, there is the potential for harm because they may assume that they are fully protected when they are not, and accordingly, alter their behavior to take unnecessary risks,” they wrote.
The U.S. Centers for Disease Control and Prevention (CDC) on Saturday said it had administered more than 4.2 million first doses of COVID-19 vaccines and distributed more than 13 million, but initial goals from the federal government estimated 20 million would be available before the end of 2020.
Pfizer’s COVID-19 vaccine, the first in the U.S., was approved by the FDA for emergency use authorization (EUA) on December 11. The FDA on December 18 also approved Moderna’s EUA request. Both are already being distributed. Moderna said its data showed their vaccine was 95% effective in its late-stage clinical trial, the same as Pfizer’s.
The Moderna vaccine was developed in conjunction with the Trump administration’s Operation Warp Speed. A key advantage of Moderna’s vaccine is that it does not need sub-zero storage like Pfizer’s, which needs to be stored at -94 degrees.
A third vaccine, one developed by AstraZeneca and researchers at Oxford University, was approved December 30 for emergency use in Britain.