The drugmakers also said in a statement that 12,000 people involved in their Phase 3 trial experienced high levels of protection against Covid-19 six months after their second dose, with no serious safety concerns.
“It is an important step to further confirm the strong efficacy and good safety data we have seen so far,” said Ugur Sahin, CEO and cofounder of BioNTech.
“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.”
The vaccine, developed by American pharmaceutical giant Pfizer and its German partner BioNTech, received emergency use authorization in December from the Food and Drug Administration, which is only granted in special circumstances.
Thursday’s trial results will allow the drugmakers to submit a full Biologics License Application to the FDA, Pfizer Chairman and CEO Albert Bourla said in the statement. They also plan to share the results with regulators around the world, and to submit the data for peer review.
The study included some 44,000 people, some of whom were given the vaccine and some a placebo. There were 927 symptomatic cases of Covid-19, only 77 of whom were given the vaccine — a 91.3 percent degree of efficacy according to the statement, which was issued by non-peer reviewed press release.
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Only one of 21 severe cases had been given the vaccine — indicating 95.3 percent efficacy, the statement said, using the Food and Drug Administration definition of severity.
Going by the Centers for Disease Control definition there were no severe cases in the vaccinated group, indicating 100 percent efficacy against severe disease, it said.
The CDC reported Monday that both the Pfizer and Moderna vaccines are extremely effective in the real world, reducing infections by 90 percent in fully vaccinated people.
The findings were the first real-world data from the United States, and are in line with similar research from other countries.
The Pfizer-BioNTech vaccine has been administered more than 76 million times in the U.S., more than Moderna’s 69 million, and Johnson & Johnson’s 3 million, according to the CDC.
Part of the trial took place in South Africa, where a variant first emerged — known as B.1.351 — which some scientists worry might be able to escape existing vaccines.
There have been 312 identified cases of this strain in the United States, according to the latest figures from the CDC.
In the Pfizer-BioNTech trial, six cases of this variant were observed, but none of them were people who had been given the vaccine — indicating an efficacy of 100 percent, it said.
This was welcomed by the drugmakers, because in February they said a laboratory test suggested that their vaccine produced lower levels of antibodies against this strain.
Although the antibody levels were lower, “it does not appear to affect the high observed efficacy against this variant,” the statement said Thursday.
This comes a day after the companies said their Covid-19 vaccine is safe and effective in teenagers between the ages of 12 and 15.
They plan to request emergency use authorization for those ages in the coming weeks.
Pfizer is also studying how well the vaccine works in children ages 6 months to 11 years old. The first doses in that trial were administered last week.