AstraZeneca stands by its COVID-19 shot despite concerns from the U.S.

SENFTENBERG, GERMANY - MARCH 03: A nurse holds a vile of the AstraZeneca vaccine against COVID-19 during the inoculation of patients at a private medical practice as part of a pilot project in the state of Brandenburg during the coronavirus pandemic on March 03, 2021 in Senftenberg, Germany. Several German states are allowing vaccinations against COVID-19 to begin in a limited number of private medical practices with the aim of expanding venues that offer the vaccines beyond the current mass vaccination centers. While Germany's vaccination rollout has been hampered by less than anticipated shipments of vaccine, the volume of shipments has begun increasing, leading to higher weekly numbers of vaccinations. (Photo by Sean Gallup/Getty Images)
A nurse holds a vile of the AstraZeneca vaccine against COVID-19. (Photo by Sean Gallup/Getty Images)

AstraZeneca says it is standing by its coronavirus vaccine despite concerns from the United States about trial results that showed the shot to be highly effective in preventing COVID-19.

AstraZeneca had published results from its U.S. trials on Monday, showing the vaccine to be 79 percent effective in preventing COVID-19, but the U.S. National Institute for Allergies and Infectious Diseases raised concerns that the results were outdated.

The firm backed its shot on Tuesday, saying a review found the interim results it had announced were “consistent”, and that it would release new analysis and data “within 48 hours”.

The uncertainties are a blow to scientists’ hopes for a quick rollout of what they say is the best hope of ending a pandemic that has killed more than 2.7 million people.

The AstraZeneca shot had been hailed as a potential game-changer in the fight against the pandemic, as it is cheaper and easier to store and transport than many of its rivals.

But public confidence in the drug has tumbled after more than a dozen countries temporarily suspended its rollout because of isolated cases of blood clots — even though the World Health Organization and regulators have found no link with the shot.

AstraZeneca has also struggled for months with production and supply chains, delivering only 30 percent of the doses it promised the European Union for the first quarter and sparking fury in Brussels.

The European Commission on Wednesday will revise trade rules to strengthen its hand when it comes to preventing exports of vaccines produced in the bloc.

As immunization programs gather pace around the world, another vaccine ran into trouble on Wednesday when Hong Kong and Macau suspended the Pfizer-BioNTech jab over what authorities said were packaging problems.

Health officials did not explain what exactly was wrong with them but insisted there were no safety issues.