(CNN) -- Drugmaker Pfizer said Monday an early look at data from its coronavirus vaccine shows it is more than 90% effective -- a much better than expected efficacy if the trend continues.
The so-called interim analysis looked at the first 94 confirmed cases of Covid-19 among the more than 43,000 volunteers who got either two doses of the vaccine or a placebo. It found that fewer than 10% of infections were in participants who had been given the vaccine. More than 90% of the cases were in people who had been given a placebo.
Pfizer said that the vaccine provided protection seven days after the second dose and 28 days after the initial dose of the vaccine. The final goal of the trial is to reach 164 confirmed cases of coronavirus infection.
In a news release, the pharmaceutical giant said it plans to seek emergency use authorization from the US Food and Drug Administration soon after volunteers have been monitored for two months after getting their second dose of vaccine, as requested by the FDA.
Pfizer said it anticipated reaching that marker by the third week of November.
The Phase 3 trial of the Pfizer vaccine, made with German partner BioNTech, has enrolled 43,538 particpants since July 27. As of Sunday, 38,955 of the volunteers have received a second dose of the vaccine. The company says 42% of international trial sites and 30% of US trial sites involve volunteers of racially and ethnically diverse backgrounds.
"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," Pfizer CEO Albert Bourla said in a statement. "We look forward to sharing additional efficacy and safety data generated from thousands of participants in the coming weeks."
Pfizer says it has added a secondary endpoint to its study. It will evaluate whether the vaccines protects people against severe Covid-19 disease and whether the vaccine can provide long-term protection against Covid-19 disease, even in patients who have been infected before.
The FDA has said it would expect at least 50% efficacy from any coronavirus vaccine.