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AstraZeneca Issues Revised Information on COVID-19 Vaccine

People wait in line for the AstraZeneca COVID-19 vaccine at San Pedro Hospital, in Logrono, northern Spain, March 24, 2021.
People wait in line for the AstraZeneca COVID-19 vaccine at San Pedro Hospital, in Logrono, northern Spain, March 24, 2021.

The ongoing drama surrounding the COVID-19 vaccine developed jointly by AstraZeneca and the University of Oxford took another turn late Wednesday when the drugmaker released updated information about its effectiveness.

The new information, based on its late-stage clinical trial involving more than 30,000 participants in the United States, shows the two-dose regimen is 76% effective in preventing symptomatic coronavirus.

The latest figures revised an announcement made by the British-Swedish pharmaceutical giant on Monday that the vaccine was 79% effective against the virus. Those claims were thrown into doubt just hours later when a key U.S. government oversight agency, the Data and Safety Monitoring Board, said AstraZeneca “may have included outdated information” from the late-stage clinical trial, “which may have provided an incomplete view of the efficacy data.”

The statement from the independent board of experts was just the latest setback for the Oxford-AstraZeneca vaccine, which has had a troubled international rollout. Several European countries had recently stopped use of the Oxford-AstraZeneca vaccine because of reports that it was associated with blood clots in recipients. South Africa stopped using the shot due to concerns about its efficacy against a local variant of the virus. The country sold at least a million of its Oxford-AstraZeneca COVID vaccines to the African Union.

However, the European Medicines Agency, the European Union’s drug approval body, has said the vaccine is safe and does not raise the overall risk of blood clots. Canada’s federal health agency announced Wednesday that it is updating the label on vials of the Oxford-AstraZeneca vaccine with information about "very rare reports of blood clots,” but continued to stand by the vaccine’s safety and effectiveness against COVID-19.

The World Health Organization has subsequently recommended the use of the Oxford-AstraZeneca vaccine against variants of the coronavirus, and said it considers the vaccine’s benefits outweigh its risks.

The Oxford-AstraZeneca vaccine has been the leading choice in the developing world because of its low cost and simple storage requirements.

The latest twist in the Oxford-AstraZeneca vaccine saga comes as the United States and Brazil reach new milestones in the yearlong pandemic. According to Johns Hopkins University’s Coronavirus Resource Center, the U.S. has now surpassed 30 million total cases, the most of any nation, while Brazil has gone beyond the 300,000 fatality mark.

Globally, more than 124.6 million people have been infected, including more than 2.7 million deaths.

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