Pfizer, BioNTech say their COVID-19 vaccine is over 90% effective

The initial analysis looked at first 94 confirmed cases among over 43,000 volunteers who either received two doses of the vaccine or placebo.

Under 10% of infections were among participants who received the vaccine while over 90% of the infections were among people who received the placebo.

The vaccine provided protection after seven days of the second dose (28 days after the first dose).

Pfizer has said the firm plans to seek emergency-use authorization from the US Food and Drug Administration for people aged 16 to 85.

For this, Pfizer will need to have collected two months of safety data after receiving the second dose of the vaccine. Pfizer is expecting this marker by the third week of November.

FDA requires at least 50% efficacy from any vaccine.

If authorized for emergency-use, the number of doses will initially be limited.

The companies had started manufacturing doses ahead of regulatory approval and are expected to produce 50 million doses by 2020-end—enough to vaccinate 25 million people.

By the end of 2021, the companies hope to produce 1.3 billion doses.

They notably have agreements with the US to provide up to 500 million doses.

The Phase III trials of Pfizer's vaccine have enrolled 43,538 participants since July 27.

Till Sunday, 38,955 of the volunteers had received a second dose of the vaccine.

The firm has said 42% of international trial sites and 30% of US trial sites involve volunteers of racially/ethnically diverse backgrounds.

Pfizer said it will continue the trial until there are 164 COVID-19 cases among participants.

Pfizer CEO Albert Bourla said in a statement, "With today's news, we are a significant step closer to providing people around the world with a much-needed breakthrough to help bring an end to this global health crisis."

Bourla added, "We look forward to sharing additional efficacy and safety data generated from thousands of participants in the coming weeks."

William Schaffner—an infectious diseases expert at Vanderbilt University School of Medicine—told Reuters, "The efficacy data are really impressive. This is better than most of us anticipated." Schaffner said the data looks promising, even though the study isn't complete.

Marylyn Addo—the head of tropical medicine at the University Medical Center Hamburg-Eppendorf—added, "Primary data are not yet available and a peer-reviewed publication is still pending."

Separately, US-based Moderna Inc.—whose mRNA vaccine is another leading candidate—is expecting the results of its large-scale trial later this month.

Meanwhile, the interim Phase III trial data for the Oxford University and AstraZeneca's vaccine candidate is expected as early as next month. This vaccine will be sold as 'Covishield' in India.

India's indigenous COVAXIN—developed by Bharat Biotech—is expected to be ready by February 2021.