The Food and Drug Administration said on Monday that vaccine developers would not need to conduct long randomized clinical trials for vaccines that have been adapted to protect against coronavirus variants.
The recommendations, which require small trials more similar to those required for annual flu vaccines, would greatly speed up the review process at a time when scientists are increasingly anxious about how variants can slow or reverse the progress made against the virus. .
The guidance was part of a list of new documents the agency released on Monday, including others dealing with how antibody treatments and diagnostic tests may need to be redone to respond to variants of the virus.
Together, they represented the federal government’s most detailed recognition of the threat that variants pose to existing coronavirus vaccines, treatments and tests, and came weeks after FDA Commissioner Dr. Janet Woodcock said the agency was developing a plan.
“The emergence of variants of the virus raises new concerns about the performance of these products,” said Woodcock in a statement on Monday. “We want the American public to know that we are using all the tools in our toolbox to combat this pandemic, including rotation as the virus adapts.”
Most vaccine manufacturers with authorized vaccines or candidates for end-stage tests have already announced plans to adjust their products to deal with vaccine variants. The Moderna and Pfizer-BioNTech vaccines use mRNA technology that companies said can be used to alter existing vaccines within six weeks, although testing and manufacturing take longer.
Moderna has already started to develop a new version of its vaccine that could be used as a booster injection against a variant of the virus originating in South Africa, known as B.1.351, which appears to impair the effectiveness of existing vaccines.
A variant of the rapidly spreading coronavirus first seen in Britain has also gained a worrying mutation that could make control with vaccines more difficult. This variant with the mutation was found in the United States last week.
Still, the guideline did not appear to have been written with the assumption that new vaccines were imminent or would be needed. Despite recent evidence that some variants – mainly B.1.351 – make vaccines currently authorized less effective, vaccines still offer protection and appear to greatly reduce the severity of the disease, preventing hospitalizations and death.
Asked at a news conference on Monday afternoon about how much the variants would need to spread before updated vaccines were needed, Dr. Woodcock did not provide 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 over us,” she said.
An updated Covid-19 vaccine could skip the process of months of a randomized clinical trial that would compare it to a placebo, the agency said. But an adjusted vaccine will still need to pass some tests. In tests proposed by the FDA, researchers will draw blood a relatively small group of volunteers who received the adapted vaccine. Scientists will then look at the percentage of samples from volunteers that produce an immune response to 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 induced by the original vaccines.
Dr. Peter Marks, the FDA’s top vaccine regulator, said at the news conference that the studies would include “a few hundred” people and would last for several months.
Volunteers will also be monitored carefully for side effects. The agency said the test could be done on a single age group and then extrapolated to other age groups.
The guidance also encouraged the use of animal studies to support the case of modified vaccines, in case immune response studies reach ambiguous conclusions.
The FDA acknowledged that many questions remained unanswered, such as what type of data would trigger the need for an adapted 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 who would protect someone from the virus.
Some other vaccines are regularly updated in a similar way. Because the flu virus evolves rapidly from one year to the next, vaccine developers need to present new recipes annually.
The newly adjusted Covid-19 vaccines would be authorized under an amendment to the emergency authorization granted to the original vaccine, regulators said.