Pfizer's vaccine is already authorized for use in people starting at age 16.
The results follow separate data that showed the vaccine is safe and effective in 12- to 15-year olds, paving the way for the drugmakers to seek USA and European approvals for this group.
There were also no serious safety concerns observed in trial participants up to six months after the second dose, the companies said. The firms said the data demonstrates the vaccine's high efficacy against this variant.
Dr. Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases, agreed that protection from these vaccines is likely to last longer than six months.
"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, Pfizer.
Pfizer and BioNTech have announced new results from their clinical trial, showing 100 percent efficacy at preventing COVID-19 cases in South Africa, where variant B.1.351 is prevalent. Thirty-two severe COVID-19 cases were recorded, all in the placebo group, translating into a 100% efficacy against severe disease for the vaccine.
The firms said that of these cases, 850 occurred among participants who got the placebo, while 77 were in the vaccinated group. For the study, the team conducted a survey of 1,090 healthcare workers at Cedars-Sinai who had received the Pfizer-BioNTech vaccine.
'The vaccine elicits such high levels of antibodies that even when confronted with a variant. there's still meaningful protection, ' Hensley told CNN.
The US drug regulator gave Moderna clearance to speed up output of its Covid-19 vaccine by letting it fill a single vial with up to 15 doses, with the United States banking on rapid immunisation to stem the spread of the deadly virus.
The efficacy level is slightly down from the 95% number the vaccine first posted in the trial.
Meanwhile, research, led by the University of Birmingham and including Public Health England's Porton Down laboratory, found 98% of people aged 80 or over who had two doses of the Pfizer jab had a strong antibody immune response.
The vaccine, which was the first in the U.S.to receive emergency use authorization from the Food and Drug Administration, is 91% effective against symptomatic disease and was even more effective at preventing severe disease, Pfizer reported.