The FDA and vaccine producers assert their confidence in the safety of doses designed to target Omicron subvariants. Now, the new Covid boosters are set to roll out without human testing.
This week, the Food and Drug Administration is anticipated to approve new Covid-19 booster shots without using data from a study demonstrating whether the shots were safe and effective in patients, a necessary component of its typical decision-making process.
The FDA will not have finished testing the vaccines in humans when it announces its decisions since they have been updated to target the most recent iterations of the Omicron variant.
The agency instead intends to evaluate the doses using information from other sources, including that of mice research, the characteristics of the original vaccines, and the effectiveness of earlier generations of boosters that were designed to target older strains of Omicron.
FDA Commissioner Robert Califf recently tweeted, “Real world evidence from the current mRNA Covid-19 vaccines, which have been administered to millions of individuals, show us that the vaccines are safe.” When prompted for comment, the FDA cited Dr. Califf’s tweets.
Clearance of the dosages without results from human trials known as clinical trials is comparable to the approach taken by the FDA with flu vaccinations, which are changed annually to keep up with evolving flu viruses.
However, several vaccination specialists have expressed reservations about the method, urging the agency to wait.
Paul Offit, an FDA expert and the head of the Vaccine Education Center at Children’s Hospital of Philadelphia, said, “I’m uncomfortable that we would move forward—that we would give millions or tens of millions of doses to people—based on mouse data.”
Dr. Offit believes the parallel with flu vaccines is flawed because flu viruses mutate so quickly that injections from one year do not provide protection for the next, whereas presently available Covid-19 shots continue to keep individuals out of the hospital.
In addition to examining the boosters in the absence of clinical-trial data, the FDA will not hold a conference of advisors who will give recommendations on whether the agency should sanction a shot.
The FDA canceled the meeting, according to Dr. Califf’s tweets on the topic, because the committee examined the problem in June and the agency has no new questions that require its input.
The Covid-19 vaccinations that are currently available in the United States were initially approved for use in December 2020; however, despite the virus they were intended to prevent evolving, they have not yet undergone any modifications.
Researchers discovered that while the shots worked effectively against older strains, they were not as successful against more recent Omicron subvariants like BA.5.
In late June, federal health officials authorized Pfizer Inc. and its partners BioNTech SE and Moderna Inc. to upgrade their shots to target BA.5, an Omicron subvariant termed BA.4, and the original strain of the virus.
“We’ve validated the process several times over and continue to produce safe and effective vaccines against Covid-19,” a Pfizer spokesperson said. According to Moderna, all existing data demonstrates that its shots are safe and effective.
Human trials for Moderna’s vaccine targeting the subvariants have begun, while the Pfizer-BioNTech vaccine is set to begin this month, according to the firms. However, results will not be accessible until after the United States government’s scheduled fall booster campaign.
“If we waited for clinical-trial results, thank you very much, we’d get them in the spring. It takes time to do clinical trials,” said William Schaffner, a professor of medicine at Vanderbilt University Medical Center and a nonvoting consultant to the Centers for Disease Control and Prevention panel that will determine whether to recommend the shots if the FDA approves. “This is just an updating of the previous vaccine that we used.”
According to John Grabenstein, director of scientific communications for Immunize.org, a nonprofit organization that works to increase immunization rates, the reconfigured shots are comparable to the original shots but tailored to combat the most recent variants, like keys that are virtually identical but have subtly different ridges and valleys.
The parallels make it extremely logical for regulators to evaluate the original series’ largely safe track record when reviewing the new shots, he said.
The FDA evaluated test data from a shot that Moderna tweaked to target an early variant of Omicron as well as the coronavirus’s ancestor strain. The study discovered that the injection produced significantly more antibodies in humans than the company’s already available booster shot. That injection is now legal in the United Kingdom.
The agency also examined human data from Pfizer and BioNTech, discovering that their experimental shots, which were altered to target an earlier type of Omicron, significantly increased antibody levels. According to Pfizer, the businesses have submitted one of those shots for approval to the United Kingdom, the European Union, and Canada.
According to a person familiar with the FDA’s deliberations, such data give the agency faith that the newest modified doses will likewise function effectively.
“As we know from prior experience, strain changes can be made without affecting safety,” Dr. Califf said in a tweet.
Dr. Offit, on the other hand, stated that he would like to wait for clinical-trial data demonstrating that the shots are helpful before requiring people to take them.
“If you have some evidence that this is likely to be of value, sure,” he said. “But if you don’t have evidence, and you know that the current vaccine does offer protection against severe disease, I don’t think it’s fair to ask people to take risks.”