Pharmaceutical company AstraZeneca on Wednesday downgraded the efficacy of its COVID-19 vaccine from 79% to 76% in an updated U.S. study after U.S. authorities urged it to revise the initial data.
The results, very similar to the original results, also indicate 85% effectiveness against symptomatic cases of COVID-19 among those over 65 years of age and 100% effectiveness against severe cases of the disease or hospitalizations. The study involved 32,449 volunteers in the United States, Chile and Peru who received either two doses of AstraZeneca’s vaccine or a placebo.
In a statement, AstraZeneca executive vice president Mene Pangalos said that “the main analysis is consistent with the previously published interim analysis and confirms that the COVID-19 vaccine is highly effective in adults, including those aged 65 years and older.” He also reiterated that the company intends to apply to U.S. authorities for emergency authorization to distribute the vaccine in the United States.
On Monday, AstraZeneca announced that its vaccine was 79% effective, which the White House described as “encouraging.”
However, an independent panel of experts advising President Joe Biden’s administration expressed concern that the data used for the study may be outdated and notified the authorities. As a result, the U.S. National Institute of Allergy and Infectious Diseases (NIAID), which is headed by Dr. Anthony Fauci, urged AstraZeneca to work with the expert panel “to revise the efficacy data and ensure that these more accurate and updated efficacy figures are made public as soon as possible.”
Last week, European countries such as Germany, France, Italy and Spain suspended use of AstraZeneca’s vaccine for a few days after thrombi were detected in some people who had received it. The United States has purchased 300 million doses of the AstraZeneca vaccine, although it has not yet authorized its use. With the doses purchased from Pfizer, Moderna and Johnson and Johnson, it has enough for its entire population.