The Food and Drug Administration said on Monday that vaccine developers would not need to conduct lengthy randomized controlled trials for vaccines that have been tailored to protect against variants of the coronavirus.
The recommendations, which require small trials closer to those required for annual flu vaccines, would greatly speed up the review process at a time when scientists are increasingly eager to learn how variants could delay or reverse progress made. against the virus.
The guide was part of a list of new documents the agency released Monday, including others that address how antibody treatments and diagnostic tests might need to be restructured to respond to variants of the virus.
Together, they represented the federal government’s most detailed acknowledgment of the threat posed by variants to existing coronavirus vaccines, treatments and tests, and came weeks after Acting FDA Commissioner Dr. Janet Woodcock said that the agency was developing a plan.
“The emergence of the virus variants raises new concerns about the performance of these products,” Dr. Woodcock said in a statement Monday. “We want the American public to know that we are using every tool in our toolbox to combat this pandemic, including rotation as the virus adapts.”
Most vaccine manufacturers with licensed vaccines or candidates in late-stage trials have already announced plans to adjust their products to address vaccine variants. The Moderna and Pfizer-BioNTech vaccines use mRNA technology that the companies say can be used to alter existing vaccines in six weeks, although testing and manufacturing would take longer.
Moderna has already started developing a new version of its vaccine that could be used as a booster vaccine against a variant of the virus that originated in South Africa, known as B.1.351, which appears to decrease the effectiveness of existing vaccines.
A rapidly spreading coronavirus variant first seen in Britain has also gained a worrisome mutation that could make it difficult to control with vaccines. That variant with the mutation was found in the United States last week.
Still, the guide did not appear to be written on the assumption that new vaccines were imminent or would be necessary at all. Despite recent indications that some variants, and in particular B.1.351, make currently licensed vaccines less effective, injections still offer protection and appear to greatly reduce disease severity, avoiding hospitalizations and deaths .
When asked at a news conference Monday afternoon how much the variants would need to spread before the updated vaccines were necessary, Dr. Woodcock did not give any specific criteria. “We need to anticipate this and work on it so that we have something in our back pocket before the threshold is upon us,” he said.
An updated Covid-19 vaccine can skip the months-long process of a randomized clinical trial that would compare it to a placebo, the agency said. But a modified vaccine will still need to undergo some testing. In the trials proposed by the FDA, researchers will draw blood from a relatively small group of volunteers who have received the adapted vaccine. The scientists will then look at what percentage of the samples from the volunteers produce an immune response to the variants in the laboratory and how large that response is. Vaccines will be considered acceptable if they produce an immune response relatively close to that elicited by the original vaccines.
Dr. Peter Marks, the FDA’s chief vaccine regulator, told the news conference that the studies would include “a few hundred” people and would last for several months.
Volunteers will also be carefully monitored for side effects. The agency said the tests could be done in a single age group and then extrapolated to other age groups.
The guide also encouraged the use of animal studies to support the case for modified vaccines, in case immune response studies yield ambiguous conclusions.
The FDA acknowledged that many unanswered questions remained, such as what kind of data would trigger the need for a tailored vaccine and who would make that decision. The agency also noted that scientists had not yet determined the minimum level of antibodies in the blood of a vaccinated person that would protect someone from the virus.
Some other vaccines are periodically updated in a similar manner. Because the influenza virus evolves rapidly from year to year, vaccine developers must come up with new recipes annually.
The recently modified Covid-19 vaccines would be authorized under an amendment to the emergency authorization granted to the original vaccine, regulators said.