Pfizer Vaccine Is Highly Effective Against Variants, Studies Find

The second new study, which was published in The Lancet, was conducted by researchers at the Israel Ministry of Health and Pfizer. It is based on more than 230,000 coronavirus infections that occurred in Israel between Jan. 24 and April 3. During that period, B.1.1.7 accounted for nearly 95 percent of all coronavirus cases in the country, which has vaccinated more than half of its population.

The researchers found that the vaccine was more than 95 percent effective at protecting against coronavirus infection, hospitalization and death among fully vaccinated people 16 and older. It also worked well in older adults. Among those 85 or older, the vaccine was more than 94 percent effective at protecting against infection, hospitalization and death.

As the percentage of fully vaccinated people in each age group grew, the incidence of coronavirus infections in that cohort fell, the researchers found. The declines in infection rates matched the timing of increasing vaccine coverage in each age group better than the start of a nationwide lockdown. The results suggest that Israel’s rapid pace of vaccination has been responsible for the decline in infections in the country.

“I’m just really happy to see this data that in the real world these vaccines are having such an amazing impact on curtailing infection and disease,” said Akiko Iwasaki, an immunologist at Yale University.

Both studies also reported that two doses of the vaccine provided significantly more protection than one dose did. In the Israel study, for example, one dose of the vaccine was 77 percent effective against death, while two doses were 96.7 percent effective.

“It absolutely emphasizes the need for the second dose,” said Dr. Kathleen Neuzil, who directs the Center for Vaccine Development and Global Health at the University of Maryland School of Medicine.

Together, the studies suggest that even with the new variants, vaccination remains a plausible path out of the pandemic, experts said. “If we can get vaccines to the world and get coverage up,” Dr. Neuzil said, “I believe we can get on top of this and we can get on top of the emergence of new variants.”