On Mar. 15, 2022, Pfizer and BioNTech announced the companies had submitted an application to the U.S. Food and Drug Administration for Emergency Use Authorization (EUA) of an additional booster dose adults 65 years of age and older who have received an initial booster of any of the authorized or approved COVID-19 vaccines. The submission was based on two real-world data sets from Israel analyzed at a time when the Omicron variant was widely circulating. Both data sets showed evidence that an additional mRNA booster increases immunogenicity and lowers rates of confirmed infections and severe illness.

An analysis of Israeli Ministry of Health records was conducted for over 1.1 million adults 60 years of age and older who had no known history of SARS-CoV-2 infection and were eligible for an additional (fourth dose) booster. These data showed rates of confirmed infections were 2 times lower and rates of severe illness were 4 times lower among individuals who received an additional booster dose of the Pfizer-BioNTech COVID-19 Vaccine administered at least four months after an initial booster (third) dose compared to those who received only one booster dose.

Also included in the submission are results from an ongoing, open-label, non-randomized clinical trial in healthcare workers 18 years of age and older at a single study center in Israel who had been vaccinated with three doses of the Pfizer-BioNTech COVID-19 Vaccine. Among the 154 (out of 700) participants who received an additional booster (fourth) dose of the Pfizer-BioNTech COVID-19 Vaccine at least four months following the initial booster, neutralizing antibody titers increased approximately 7-fold to 8-fold at two and three weeks after the additional booster (fourth) dose compared to five months after the initial booster (third) dose. Additionally, there was an 8-fold and 10-fold increase in neutralizing antibody titers against the Omicron variant (B.1.1.529) at one and two weeks after the additional booster dose, respectively, compared to five months after the initial booster. The study also revealed no new safety concerns in individuals who received an additional booster dose of the vaccine.

Emerging evidence, including data from Kaiser Permanente Southern California (KPSC), suggests that effectiveness against both symptomatic COVID-19^1,2,3,4,5 and severe disease^1,5 caused by Omicron wanes 3 to 6 months after receipt of an initial booster (third) dose. Thus, additional booster doses may be needed to ensure individuals remain adequately protected. The data being reviewed by the FDA from Israel suggest that an additional booster dose of the Pfizer-BioNTech COVID-19 Vaccine administered at least 4 months after an initial booster dose could restore antibody titers to peak post-third dose titer levels, improve protection against both infection and severe disease in individuals 60 years of age and older in Israel, and have a similar safety profile to that of previous doses.6 The data from KPSC were provided to the FDA as an example of waning of the Pfizer-BioNTech COVID-19 Vaccine, but have not been reviewed by the agency.

The Pfizer-BioNTech COVID-19 Vaccine is currently authorized as a single booster dose administered at least five months after completion of a primary series of the Pfizer-BioNTech COVID-19 Vaccine or COMIRNATY® (COVID-19 Vaccine, mRNA) to individuals 12 years of age and older. A single booster dose can also be administered to individuals 18 years of age and older who have completed primary vaccination with another authorized or approved COVID-19 Vaccine. Clinical and real-world data continue to show that people who are vaccinated, particularly those who have received a booster, maintain a high level of protection, particularly against severe disease and hospitalization. The companies remain vigilant and continue to collect data to explore new vaccine approaches and regimens to reduce the risk of infection and the risk of severe COVID-19 disease.