US health agency says AstraZeneca may have included ‘outdated information’ in its vaccine trial, in a fresh setback for the shot.

Nigeria has began mass COVID-19 vaccinations, with the AstraZeneca vial, and questions continues to be raised about the British drugmaker vaccine.

The vaccine developed with Oxford University was 79% effective in preventing symptomatic illness in the large trial that also took place in Chile and Peru, according to the data. It was also 100% effective against severe or critical forms of the disease and hospitalisation and posed no increased risk of blood clots.

The Data Safety Monitoring Board (DSMB), an independent committee overseeing the trial, has “expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data,” the U.S. National Institute of Allergy and Infectious Diseases (NIAID) said in a statement.

NIAID is headed by U.S. infectious diseases expert Anthony Fauci and is part of the National Institutes of Health.

“We urge the company to work with the DSMB to review the efficacy data and ensure the most accurate, up-to-date efficacy data be made public as quickly as possible,” it said, adding that the DSMB had informed AstraZeneca of its concerns.