closeup of booster shot bottle
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Pfizer and BioNTech announced Tuesday night that they submitted an application to the U.S. Food and Drug Administration for emergency use authorization of an additional COVID-19 booster dose for older adults to bolster waning immunity after the first booster dose.

The companies said in a release the submission is based on two real-world data sets from Israel analyzed during the omicron spike. Both data sets, they said, showed evidence that “an additional mRNA booster increases immunogenicity and lowers rates of confirmed infections and severe illness.”

An analysis of over 1.1 million adults 60 and older found that infection rates were two times lower, whereas rates of severe illness were four times lower, in those who received an additional booster dose of the Pfizer-BioNTech COVID-19 vaccine. The fourth doses were administered at least four months after the initial booster dose and compared to those who received only one booster dose.

The submission also included results from an ongoing clinical trial in healthcare workers 18 and older at a single study center in Israel who had been vaccinated with three doses of the Pfizer- BioNTech vaccine. In that study, antibody levels increased seven- to eight-fold two to three weeks after the second booster, compared to five months after the first booster shot. That study also showed a corresponding increase in neutralizing antibodies against the omicron variant after the additional dose.

The company pointed to “emerging evidence” suggesting the effectiveness against both symptomatic COVID-19 and severe disease for omicron wanes three to six months after the third dose. 

The companies said these early studies indicate an additional fourth booster dose given at least four months after the initial (third) booster dose, could improve protection against both infection and severe disease. 

In August, both the FDA and the Centers for Disease Control and Prevention gave full approval of the Pfizer Comirnaty vaccine for use in people 16 and older, and authorized its use in children five to 15 years old. The Modern vaccine was the second COVID-19 vaccine to receive full approval from both the FDA and the CDC.