Pfizer and BioNTech have initiated the submission of a supplemental Biologics License Application to the Food and Drug Administration (FDA) for a booster (third) dose of Comirnaty® (COVID-19 vaccine, mRNA) to prevent COVID-19 in individuals 16 years of age and older. The complete submission of the application is expected by the end of this week.

The application includes data from a phase 3 trial ( Identifier: NCT04955626) that evaluated the efficacy, safety and tolerability of a booster dose of Comirnaty in 306 adult participants 18 to 55 years of age who were previously vaccinated with a 2-dose primary regimen. Participants received a booster dose of Comirnaty between 4.8 and 8 months after administration of the second dose, with a median follow-up time of 2.6 months post-booster.

Results showed that the booster dose elicited robust neutralizing antibodies against the wild-type strain in participants who were without evidence of SARS-CoV-2 infection through 1 month after the third dose. Moreover, SARS-CoV-2 neutralizing titers 1 month after the booster dose were reported to be 3.3 times the titers observed 1 month after the second dose. 

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Findings also showed that the neutralizing titers after the booster dose met the prespecified 1.5-fold noninferiority criterion for success and were statistically superior. A 4-fold response was observed in 99.5% of participants after the booster dose compared with 98% after the second dose. The titers after the booster dose also met the prespecified 10% noninferiority margin for the difference in the 4-fold seroresponse rates. 

The most common adverse reactions reported were injection site pain, fatigue, headache, muscle and joint pain, and chills.

The Companies plan to submit the study data to a peer-reviewed journal and other regulatory authorities in the coming weeks.

In August 2021, the FDA authorized for emergency use the administration of a third dose of the Pfizer-BioNTech COVID-19 vaccine to individuals at least 12 years of age who have undergone solid organ transplantation, or who are diagnosed with conditions that are considered to have an equivalent level of immunocompromise.


Pfizer and BioNTech initiate rolling submission of supplemental Biologics License Application to US FDA for booster dose of Comirnaty® in individuals 16 and older. News release. Pfizer, Inc and BioNTech SE. Accessed August 25, 2021.

This article originally appeared on MPR