Pfizer/BioNTech COVID-19 vaccine remains highly effective after 6 months, trial data show

A caregiver shows a bottle of the Pfizer-BioNTech COVID-19 vaccine in a Health Centre in Alfortville, near Paris, France, on Jan. 8, 2021. (Photo by Aurelien Morissard/Xinhua)

The Phase 3 study showed the Pfizer-BioNTech COVID-19 vaccine was 91.3 percent effective against COVID-19, measured seven days through up to six months after the second dose.

WASHINGTON, April 1 (Xinhua) -- The ongoing Phase 3 clinical trial of Pfizer/BioNTech's COVID-19 vaccine showed its protection remains high for up to six months after the second dose, the two companies announced on Thursday.

Results from the analysis of 927 confirmed symptomatic cases of COVID-19 observed in their pivotal Phase 3 study showed the Pfizer-BioNTech COVID-19 vaccine, BNT162b2, was 91.3 percent effective against COVID-19, measured seven days through up to six months after the second dose.

The vaccine was 100 percent effective against severe disease as defined by the U.S. Centers for Disease Control and Prevention, and 95.3 percent effective against severe COVID-19 as defined by the U.S. Food and Drug Administration (FDA), according to a joint statement of the two companies.

Safety data from the Phase 3 study have been collected from more than 12,000 vaccinated participants who have a follow-up time of at least six months after the second dose, demonstrating a favorable safety and tolerability profile, said the statement.

"These data confirm the favorable efficacy and safety profile of our vaccine and position us to submit a Biologics License Application to the U.S. FDA," said Albert Bourla, chairman and chief executive officer of Pfizer.

"These data also provide the first clinical results that a vaccine can effectively protect against currently circulating variants, a critical factor to reach herd immunity and end this pandemic for the global population," said Ugur Sahin, CEO and co-founder of BioNTech.

A woman receives the first dose of the Pfizer-BioNTech COVID-19 vaccine at Sao Domingos de Rana sports complex, in Cascais, Lisbon, Portugal, on Feb. 18, 2021. (Photo by Pedro Fiuza/Xinhua)

The new results came a day after the two companies announced the vaccine has demonstrated 100 percent efficacy and robust antibody responses in a trial in adolescents 12 to 15 years of age.

The trial enrolled 2,260 adolescents 12 to 15 years of age in the United States. In the trial, 18 cases of COVID-19 were observed in the placebo group versus none in the vaccinated group.

The vaccine elicited SARS-CoV-2-neutralizing antibody geometric mean titers (GMTs) of 1,239.5, demonstrating strong immunogenicity in a subset of adolescents one month after the second dose, according to the companies.

The results exceeded those recorded earlier in vaccinated participants aged 16 to 25 years old, according to the trial data.

The two companies plan to submit these data to the FDA and the European Medicines Agency as soon as possible to request expansion of the Emergency Use Authorization and EU Conditional Marketing Authorization for BNT162b2.

The FDA authorized Pfizer-BioNTech COVID-19 vaccine for emergency use in the United States in December last year. The vaccine, the first that got FDA approval in the country, was authorized for use in individuals 16 years of age and older.