Pfizer says early data signals COVID-19 vaccine is effective

Pfizer reported Monday early data from an interim analysis indicating that its vaccine appears highly effective at preventing COVID-19. The analysis, from an independent data monitoring board, examined 94 infections recorded thus far in a study that has enrolled almost 44,000 individuals in six countries, including the United States. According to the data, the vaccine—which Pfizer developed with the German drugmaker BioNTech—may be 90% effective in preventing infection. Further details about those cases were not provided, and the company warned the initial protection rate could change by the end of the study. “We’re in a position potentially to be able to offer some hope,” said Bill Gruber, MD, Pfizer’s senior vice president of clinical development. “We’re very encouraged.” He noted that none of the participants so far has become seriously ill. The study has not yet ended, and Pfizer does not plan to stop the trial until it records 164 infections among all the volunteers—a number FDA has agreed is sufficient to determine how well the vaccine is working. Participants were also only tested if they developed COVID symptoms, raising questions about whether people who have been vaccinated could become infected but have no symptoms and unknowingly spread the novel coronavirus.