Pfizer/BioNTech COVID-19 Vaccine More Than 90 Percent Effective, Early Data Reveals

Pfizer and BioNTech have pulled ahead to become the frontrunners in the race for a COVID-19 vaccine, announcing that the first interim analysis from their late-stage trial showed the candidate was more than 90 percent effective.

Pfizer CEO Albert Bourla unveiled the results Monday, calling the event “a great day for science and humanity.” The analysis, which evaluated 94 participants with confirmed cases of COVID-19, found that the vaccine was more than 90 percent effective at preventing symptomatic COVID-19 infections, meaning the overwhelming majority of vaccinated patients developed few to no symptoms.

Pfizer, which is developing the vaccine jointly with Germany-based BioNTech, remains on track to submit a request for an Emergency Use Authorization (EUA) to the FDA in the third week of this month, when it will have collected the safety data as required by agency regulations. Moderna also anticipates filing an EUA application for its vaccine candidate around the same time (DID, Oct. 21).

Pfizer expects to manufacture up to 50 million doses of the vaccine in 2020 and up to 1.3 billion doses in 2021. But distribution will be challenging: the vaccine needs to be stored at ultra-cold temperatures.

According to the interim analysis unveiled Monday, the BNT162 vaccine proved to be effective seven days after the second dose, meaning protection was achieved 28 days after starting the two-dose vaccine. The final rate of efficacy “may vary,” the Pfizer chief said, but the effectiveness seen in the interim analysis is far above expectations. The vaccine candidate also seems incredibly safe, with no serious safety issues reported to date.

The phase 3 study will continue to a final analysis after 164 participants are confirmed to have been infected with COVID-19 “in order to collect further data and characterize the vaccine candidate’s performance against other study endpoints,” the company said. To date, the trial has enrolled 43,538 participants.

Pfizer’s and BioNTech’s candidate is based on an unproven vaccine technology, messenger RNA (mRNA), that uses mRNA to trick the body into producing viral proteins itself and set off a defensive immune response. Moderna’s vaccine candidate is also based on the mRNA technology (see related story).

“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 said. “We look forward to sharing additional efficacy and safety data generated from thousands of participants in the coming weeks.”

The scientific community welcomed the preliminary data as very promising. Shane Crotty, a virologist and professor at La Jolla Institute for Immunology, called the effectiveness rate “a truly excellent and important outcome,” while Bob Wachter, chair of UC San Francisco’s Department of Medicine, called the results “far better than even most optimistic projections.”

“We don’t know yet how well this vaccine prevents severe symptoms that lead to hospitalizations, intensive care unit admissions and death,” Wachter said. “That’ll be key. It seems likely it will, but that still needs to be demonstrated.” — James Miessler