The findings in Scotland bolstered earlier results from Israel showing that the vaccines offered significant protection from the virus. The Israeli studies have focused on the Pfizer vaccine, but the Scottish study extended to the AstraZeneca shot, which has been administered in Britain since early January. The AstraZeneca shot is the backbone of many nations’ inoculation plans: It is far cheaper to produce, and can be shipped and stored in normal refrigerators rather than the ultracold freezers used for other vaccines.
“Both of these are working spectacularly well,” Aziz Sheikh, a professor at the University of Edinburgh who was involved in the study, said at a news conference on Monday.
The researchers in Scotland examined roughly 8,000 coronavirus-related hospital admissions, and studied how the risk of hospitalization differed among people who had and had not received a shot. Over all, more than 1.1 million people were vaccinated in the period the researchers were studying.
The numbers of vaccinated people who sought care in hospitals was too small to compare the AstraZeneca and Pfizer vaccines, or to give precise figures for their effectiveness, the researchers said.
But from 28 to 34 days after the first shot, the AstraZeneca vaccine reduced the risk of Covid-19 hospital admissions by roughly 94 percent. In that same time period, the Pfizer vaccine reduced the risk of hospitalizations by roughly 85 percent. In both cases, those figures fit within a broad range of possible effects.