FDA scientists propose an annual Covid shot matched to current strains

Scientists at the Food and Drug Administration propose making Covid vaccination a regular, once-a-year shot that is updated to match current strains of the SARS-CoV-2 virus, according to documents posted by the FDA on Monday.

For people who are older or immunocompromised, the FDA would recommend two annual doses of the revised shot.

The new proposals were outlined ahead of a Thursday meeting of the FDA’s advisory panel on vaccines and related biological products, which will be asked to give the agency feedback on its plan. The committee will be asked to vote only on whether the existing vaccines, which are based on the original strain of SARS-CoV-2 that circulated in 2020, should be changed to match the current booster shots, which contain both the original strain and the newer Omicron strain.

The committee will also be asked to discuss moving to a one-dose vaccine for most people, with a two-dose series for young children, older adults, and those with compromised immune systems, and to provide guidance on how to make periodic updates to the vaccines in order to match current circulating strains of SARS-CoV-2.

The FDA convenes expert committees to get guidance, but is not bound by their votes or recommendations. Still, it usually follows their advice.

Some recent high-profile votes have seemed to show an unusual tension between the regulator and its advisory committees, however. Six members of the committee, including its acting chair, recently told CNN that they were disappointed that the FDA did not present data to them about the number of cases of infection in trials of the booster shot made by Moderna, although they also said it would not have changed their vote.

And the agency was recently criticized by two congressional committees for the way it handled the advice of a different expert committee, on the Alzheimer’s drug Aduhelm. The committee recommended rejecting the drug, but the agency approved it. The decision was widely criticized and the medicine has barely been used.

In November 2021, the FDA chose to widely approve Covid boosters for all individuals. That September, the advisory committee had recommended booster shots be limited to those 65 and older.

One of the key questions about the new proposal on Covid vaccines is what degree of evidence is required for the new boosters. The Covid vaccines manufactured by Pfizer/BioNTech, Moderna, Novavax, and Johnson & Johnson were all originally tested in large clinical trials where patients were randomized to receive either the vaccines or a placebo. All of these studies showed dramatic efficacy against the original strain.

But a rare safety concern and lower efficacy resulted in use of the J&J vaccine plummeting, and manufacturing and regulatory issues kept Novavax’s vaccine off the market, making the Pfizer and Moderna shots the main ones that are used in the U.S. For younger children, the Pfizer vaccine currently requires a three-dose series, not a two-dose one.

The immunity provided by the shots waned both because it tended to decrease over time and because newer strains of the SARS-CoV-2 virus were better at evading it. Giving booster shots increased this immunity, both against the original strain and against newer ones.

What has been less clear is whether updating the booster to match the current Omicron strain as well as the original strain of SARS-CoV-2 granted added protection. The FDA’s scientists present a wealth of studies showing that the new boosters increase antibody levels for people who were previously vaccinated with the original vaccine.

They also present observational studies, in which researchers collect data from the real world and try to control for variables that might change the study result, that suggest the new boosters are protective.

One study, of a national Covid testing program, showed that the efficacy of two doses of the original vaccine against symptomatic Covid was 30% in people 18 to 49 years of age, compared to 58% for those who received the booster. For those 50 to 64 years old, those figures were 31% and 48%, and for those over 65 they were 28% and 43%.

But the most important role of a vaccine is preventing hospitalization and death, not symptoms. A second study using a different database showed that a booster dose of the newer vaccine reduced emergency department and urgent care visits by 56% compared to no vaccine at all. For those who had received their last vaccine dose a year ago, the reduction in ED and urgent care visits was 50%.

A third study, conducted when the BA.5 Omicron variant was circulating, showed an even higher efficacy against Covid hospitalization in those over 65: 73% compared to those with previous vaccination with the original vaccines.

The FDA scientists also point to a recent study, conducted in Israel, comparing the benefits for those 65 years and older who received the new booster in Israel to those who did not. Those who received the booster were 81% less likely to be hospitalized and 86% less likely to die. The study has not yet been peer-reviewed.

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