New vaccines are falling short of the spectacular expectations set by Pfizer and Moderna. The world still needs them.
Last spring and summer, when a COVID-19 vaccine was only a glimmer of hope on the horizon, scientists warned in their careful way that vaccines might not live up to the public’s high expectations. The FDA said a vaccine needed to be just 50 percent effective. The most important thing, scientists told me, was that the vaccines at least protect against severe illness.
Then, in the fall, data from the Pfizer and Moderna vaccine trials demonstrated 95 percent and 94 percent efficacy, respectively, against all symptomatic infections. They smashed expectations—and created new ones. In comparison, the results from other vaccine trials look pretty good but unspectacular: AstraZeneca’s vaccine looks to be 70 percent effective; Novavax’s achieved 89 percent efficacy in the U.K., but only 49 percent in South Africa, based on data released yesterday; and Johnson & Johnson’s demonstrated 66 percent efficacy against moderate and severe infection, based on results released today. These numbers are not directly comparable because the different trials were run in different countries, with slightly different protocols, against different versions of the virus. The lower efficacy in South Africa results is likely related to a new variant of the coronavirus, which seems to have evolved to escape immunity.
But beneath these top-line numbers is a consistent pattern: All of the vaccines are very good at preventing severe illness and death from COVID-19. That was the original goal for the vaccines, and it is still the most important. “We’re most interested in our ability to keep people out of the hospital and keep people alive,” says Natalie Dean, a biostatistician at the University of Florida.