AstraZeneca Plc said Wednesday that its coronavirus vaccine was 76 percent effective at preventing symptomatic illness in a clinical trial, slightly lowering the rate after facing questions in the United States over its data.
An interim analysis of the trial, which took place in the United States, Peru and Chile, showed Monday that the vaccine efficacy was 79 percent.
But the U.S. National Institute of Allergy and Infectious Diseases said a day later that the British company may have included "outdated" information from the trial when reporting the results, possibly providing an "incomplete view of the efficacy data."
AstraZeneca said the primary analysis released Wednesday was based on 190 symptomatic cases of COVID-19, the respiratory illness caused by the virus, among more than 32,400 participants. The interim analysis was based on 141 cases through Feb. 17.
Vaccine efficacy was 85 percent in adults 65 years and older in the updated analysis, the company said. No safety concerns related to the vaccine were identified.
"The primary analysis is consistent with our previously released interim analysis, and confirms that our COVID-19 vaccine is highly effective in adults, including those aged 65 years and over," AstraZeneca said in a press release.
The company also said it is looking forward to seeking emergency use authorization in the United States.
