FDA expected to allow mix and match COVID-19 boosters

The Food and Drug Administration (FDA) is expected to give the go ahead this week to mixing and matching COVID-19 vaccine booster shots.

According to a report from The New York Times, the agency is expected to allow patients who received one COVID-19 vaccine to receive a booster shot of a different authorized vaccine in a move that would offer flexibility to both patients and physicians.

The topic was discussed Oct. 15 during a meeting of the FDA Vaccines and Related Biological Products Advisory Committee where emergency use authorization expansions for the Moderna and Johnson and Johnson vaccine were deliberated. According to documents reviewed at the meeting, receiving a booster of a different COVID-19 vaccine than the initial doses elicited similar or higher protection compared to a booster matching the initial doses.

Furthermore, the mRNA vaccines resulted in higher antibody titers in the first 28 days after the booster shot and no safety concerns were identified, according to the documents.

Last week, the panel approved an emergency use authorization for the half-dose of the Moderna vaccine to be administered six months after the initial two-dose regimen for those considered at high risk of severe COVID-19 infection; the same groups eligible for the Pfizer booster shot.

The committee also voted unanimously to recommend boosters of the Johnson and Johnson vaccine for all adults two months after the initial dose.

Documents which the committee used to reach their determination show that, when administered six months after a second dose, the booster dose of the Moderna vaccine raise antibody titers 15 times a month after the additional shot and provides protection against the now-dominant Delta variation of the disease.

The documents also show that the booster shots appear safe, with the reactogenicity and adverse event profile similar to that seen after the second dose of the vaccine.

A Phase 3 ENSEMBLE 2 study found that a second dose of the Johnson and Johnson vaccine administered 56 days after the first provided 100 percent protection against severe or critical COVID-19, 75 percent protection against symptomatic COVID-19 globally, and 94 percent protection against symptomatic COVID-19 in the U.S. When the second shot is administered, it boosts antibody levels four to six times higher than what is observed after the initial dose.

When the booster shot was given six months after the initial dose antibody levels shot up nine-fold after a week and 12-fold after four weeks irrespective of the age of the patient.

The committee will reconvene on Nov. 30 to discuss the Merck investigational antiviral pill, molnupiravir, for the treatment of mild-to-moderate COVID-19 in adults.

As previously reported, a planned interim analysis of a Phase 3 MOVe-OUT trial in 775 at risk, non-hospitalized adult patients with mild to moderate COVID-19 found that the antiviral reduced the risk of hospitalization or death by 50 percent. No patients who received the pill died after 29 days compared to eight who died after receiving a placebo.

The company plans to produce 10 million courses of treatment by the end of the year and previously entered into an agreement with the federal government to supply about 1.7 million courses of molnupiravir upon receiving an EUA or approval from the FDA. Merck has struck similar deals with other countries.