BioNTech reiterated this week there would likely be a future need for booster shots that specifically address new variants and that the group was preparing to upgrade its vaccine when needed.
The vaccine remains more than 91% effective against disease with any symptoms for six months, the companies said in a statement.
Pfizer and BioNTech say their COVID-19 vaccine is about 91 per cent effective at preventing the disease, citing updated trial data that included participants inoculated for up to six months.
Earlier this week, Pfizer reported that its vaccine was 100% effective in 12 to 15 year olds during clinical trials.
Ian Haydon helped test Moderna's coronavirus vaccine a year ago. A spokeswoman said on Thursday its strategy remains in place. "These data also provide the first clinical results that a vaccine can effectively protect against now circulating variants, a critical factor to reach herd immunity and end this pandemic for the global population".
Pfizer's vaccine is already authorized for use in people starting at age 16. "The high vaccine efficacy observed through up to six months following a second dose and against the variant prevalent in South Africa provides further confidence in our vaccine's overall effectiveness".
"It's unclear whether this new tweaked version is even going to be necessary", Haydon told CNN in a telephone interview.
Since that initial analysis, more COVID-19 cases have accrued, increasing to 927 as of March 13 from the previous 170.
The firms said that of these cases, 850 occurred among participants who got the placebo, while 77 were in the vaccinated group.
"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.
The efficacy level is slightly down from the 95% number the vaccine first posted in the trial.
But he added it will be crucial to see how long antibody levels are maintained after people have had a Covid-19 vaccine.
Both Pfizer and Moderna use a technology called messenger RNA or mRNA delivery as the basis of their vaccines.
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.
Pfizer and BioNTech said Thursday their Covid-19 vaccine was highly effective against the South African variant in the latest phase of ongoing clinical trials.
Deadly train derailment in Taiwan
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Egyptian mummies move to new home
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Ontario back into shutdown starting April 3
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