The second new study, published in The Lancet, was carried out by researchers from the Israel Ministry of Health and Pfizer. It is based on more than 230,000 coronavirus infections that occurred in Israel between January 24th and April 3rd. During that period, B.1.1.7 accounted for nearly 95 percent of all coronavirus cases in the country, more than half of which were vaccinated in its population.
The researchers found that the vaccine was more than 95 percent effective against coronavirus infections, hospitalizations, and deaths in people aged 16 and over who were fully vaccinated. It also worked well in older adults. Among those 85 years of age or older, the vaccine was more than 94 percent effective against infections, hospitalizations, and deaths.
As the percentage of people fully vaccinated increased in each age group, the incidence of coronavirus infections decreased in this cohort, the researchers found. The decline in infection rates was more in line with when vaccine coverage was increased in each age group than when a nationwide lockdown began. The results suggest that Israel's rapid pace of vaccination was responsible for the decline in infections in the country.
"I'm just so happy to see this data that these vaccines have such an amazing impact in the real world in containing 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. For example, in the Israel study, one dose of the vaccine was 77 percent effective against death, while two doses were 96.7 percent effective.
"It absolutely underscores 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.
Taken together, the studies suggest that vaccination remains a plausible way out of the pandemic even with the new variants, experts said. "If we can get vaccines out into the world and improve reporting," said Dr. Neuzil, "I believe that we can go beyond that and stay up to date on the emergence of new variants."