Drugmaker company Pfizer announced last Monday, November 9, that its coronavirus vaccine showed 90% efficiency based on an early look at data. The interim analysis studied the first 94 positive cases out of 43,000 volunteers who took two doses of the vaccine. Less than 10% of infection was found in participants who took the vaccine shots. According to Pfizer, the vaccine achieved its 90% efficiency rate seven days after the second shot. This means it will take 28 days for a person to be immune from the virus, and it is required for an individual to take two doses of the vaccine.

Pfizer’s Phase 3 trial has had about 43,538 volunteers since July 27 and 38,955 of them have received the second dose of the vaccine. The company’s final goal is to administer the vaccine to 164 patients with positive cases. Pfizer also intends to evaluate if the vaccine can provide long-term protection against the coronavirus even to patients who had been infected before. As for the shots distribution, it is still unclear if it will be done yearly or seasonal. “I think it is a likely scenario that you will need periodical vaccinations,” Pfizer CEO Albert Bourla said.