The Food and Drug Administration said Monday that vaccine developers would not have to conduct lengthy randomized controlled trials for vaccines adapted to protect against coronavirus variants.

The recommendations, which require small studies that are closer to those required for annual flu vaccines, would greatly speed up the review process at a time when scientists are increasingly concerned about how the variants could slow or reverse progress against the virus.

The guidelines were part of a list of new documents the agency released on Monday, including others addressing how antibody treatments and diagnostic tests may need to be retooled to respond to the virus variants.

Together, they represented the federal government’s most detailed recognition of the threat the variants pose to existing vaccines, treatments, and tests for the coronavirus, and came weeks after Acting FDA Commissioner Dr. Janet Woodcock said the agency was developing a plan.

“The emergence of the virus variants raises new concerns about the performance of these products,” said Dr. Woodcock in a statement Monday. “We want the American public to know that we are using every tool in our toolbox to help fight this pandemic, including panning as the virus adapts.”

Most vaccine manufacturers with approved vaccines or candidates in late-stage studies have already announced plans to adapt their products to the vaccine variants. Moderna and Pfizer-BioNTech’s vaccines use the companies’ specified mRNA technology, which allows existing vaccines to be modified in six weeks, although testing and manufacturing would take longer.

Moderna has already started developing a new version of its vaccine that can be used as a booster shot against a variant of the virus native to South Africa called B.1.351, which appears to be dampening the effectiveness of existing vaccines.

A fast-spreading variant of coronavirus, first observed in the UK, has also received a worrying mutation that could make vaccine control difficult. This variant with the mutation was found in the US last week.

However, the guidelines did not appear to be written with the assumption that new vaccines were imminent or needed at all. Despite recent evidence that some variants – and B.1.351 in particular – are interfering with the effectiveness of currently approved vaccines, the shots still offer protection and appear to significantly reduce the severity of the disease, preventing hospitalizations and death.

At a press conference on Monday afternoon, asked how much the variants would have to spread before updated vaccines would be required, Dr. Woodcock does not have any specific criteria. “We have to anticipate this and work on it so that we have something in our back pocket before the threshold is above us,” she said.


Apr. 22, 2021, 8:11 p.m. ET

An updated Covid-19 vaccine can skip the month-long process of a randomized clinical trial that would compare it to a placebo, the agency said. However, an optimized vaccine has yet to be tested. In studies proposed by the FDA, researchers will draw blood a relatively small group of Volunteers who received the customized vaccine. The scientists will then observe what percentage of the samples from volunteers elicit an immune response to the variants in the laboratory and how large this reaction is. The vaccines are judged acceptable if they elicit an immune response relatively close to that elicited by the original vaccines.

Dr. Peter Marks, the FDA’s chief vaccine regulator, said at the press conference that studies would include “a few hundred” people and would take several months.

Volunteers are also 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 guidelines also recommended the use of animal studies to support the case of modified vaccines in case immune response studies lead to ambiguous conclusions.

The FDA acknowledged that many questions remained unanswered, such as: B. what kind of data would trigger the need for a customized vaccine and who would make that decision. The agency also found that the scientists had not yet determined the minimum levels of antibodies in a vaccinated person’s blood that would protect someone from the virus.

Some other vaccines are regularly updated in a similar way. Because the influenza virus evolves rapidly from year to year, vaccine developers have to come up with new recipes every year.

The newly optimized Covid-19 vaccines would be approved according to a change in the emergency approval for the original vaccine, according to regulators.