Researchers studying records of 1.7 million adults who received the AstraZeneca PLC Covid-19 vaccine in Scotland found a small increased risk of bleeding conditions also sometimes associated with several vaccines routinely given to children, and usually treatable.
The blood disorders are different from a very rare but sometimes deadly blood-clotting condition that—coupled with low platelet levels—researchers in Europe have already linked to the AstraZeneca vaccine. That possible side effect has been the focus of regulatory and government scrutiny in recent months.
In the new paper, published Wednesday in the journal Nature Medicine, researchers from the U.K. and New Zealand said their findings shouldn’t change policies in the U.K. and elsewhere to continue deploying the AstraZeneca shot as a generally safe and effective tool against Covid-19. AstraZeneca and regulators have said they are studying the blood-clotting matter further and that the benefits of the shot outweigh risks for most people. AstraZeneca said Wednesday that more than 500 million doses of the vaccine have helped save more than 100,000 lives, and that its safety is paramount.
The new analysis concludes that the benefits of the AstraZeneca vaccine, along with heightened risks of internal bleeding and blood clots from Covid-19 itself, far outweighed any increased risks from the shot for most people. Because incidents of blood clotting have occurred more often in younger adults, some health officials have said that they should be offered an alternative to the AstraZeneca shot.
The vaccine was developed with the University of Oxford. The new paper, which hasn’t been peer reviewed, provides a deeper dive into a large number of vaccine recipients in a single country. Because these bleeding conditions have been associated with other, long-used vaccines, researchers decided to study potential occurrences in Covid-19 vaccines.