Covid: AstraZeneca vaccine is associated with cardiac risk – 03/29/2023 – Health

Young women who received at least one dose of the Covid-19 vaccine produced by AstraZeneca may have been more likely to die of a heart condition in the 12 weeks after vaccination, according to an analysis of immunization and death records in Britain released today. last Monday (27).

Those findings include a big caveat: Britain suspended use of the AstraZeneca vaccine for people under 30 in April 2021, citing the risk of rare but dangerous blood clots. At that time, young women vaccinated were mostly healthcare workers or medically vulnerable people, because people at high risk of Covid due to age, health or employment were vaccinated first. Therefore, the results of the study may not apply to the general population.

“Perhaps people who are extremely vulnerable from a clinical point of view are more susceptible to the side effects of the vaccine,” said Vahé Nafilyan, senior statistician at Britain’s Office for National Statistics and one of the lead researchers on the study. The results were published on Monday in the journal Nature Communications.

The AstraZeneca vaccine was never authorized for use in the United States.

The analysis found six heart-related deaths per 100,000 young women who received at least one dose of the vaccine in Britain. In these women, heart-related death was 3.5 times more likely in the 12 weeks after vaccination than after the 12-week period. Clots that block blood flow can cause a heart attack or stroke.

The researchers did not find a significantly increased risk of death in any other subgroup or with the Pfizer-BioNTech mRNA vaccine, which was also widely used in Great Britain. And the study did not prove that vaccines caused the deaths.

The benefits of Covid vaccines still largely outweigh the risks, and the incidence of harmful events following vaccination remains very low, the researchers and other experts stressed.

In the analysis, Covid was associated with one additional death for every 12,000 unvaccinated young people and one additional death for every 56,000 young people vaccinated.

“When you look at the side effects of vaccination, I think it’s really important to see the benefits as well,” Nafilyan said.

The researchers linked immunization records to deaths from any cause recorded in people ages 12 to 29. They looked at data from December 8, 2020, when vaccination began in Britain.

Mortality data came from two independent sources: deaths recorded up to June 8, 2022 and hospital deaths up to March 31, 2022.

The team found a very small increase in deaths in the 12 weeks after vaccination in young men who received the mRNA vaccine, but said the finding was not statistically significant. Only young women — just over 177,000 — who received a dose of AstraZeneca had an increased risk of death.

The analysis does not conclusively link vaccines to deaths, experts warned.

“It’s enough to get my attention and say we should study this more,” said Daniel Salmon, director of the Vaccine Safety Institute at the Bloomberg School of Public Health at Johns Hopkins University. But “I wouldn’t come close to drawing any causal conclusions.”

“Overall, it’s pretty reassuring, but it does highlight some vaccines and some populations that deserve further study,” Salmon said.

Other studies have linked vaccine side effects to specific subgroups. Data from several countries link mRNA Covid vaccines to an increased risk of myocarditis and pericarditis —inflammation of the heart or its outer lining—, particularly in men between the ages of 12 and 29.

Within weeks of its introduction, the AstraZeneca vaccine was associated with a rare blood clotting disorder, mostly in young women, in Britain and other European countries. While the AstraZeneca vaccine has not gained regulatory approval in the United States, the Food and Drug Administration (FDA) in December 2020 authorized a similar vaccine made by Johnson.

In April 2021, the FDA called for a pause in the use of this vaccine, following reports of a blood clotting disorder in six American women. The agency withdrew the recommended break ten days later and changed the vaccine label to warn of the risk.

A year later, the FDA again restricted the vaccine’s use, saying it should only be offered to people who couldn’t or wouldn’t opt ​​for one of the mRNA vaccines. Until then, the agency had received reports of 60 cases of clotting disorders and nine deaths, in 18 million doses administered.

“Fortunately, as more and more of this data is collected and disseminated, we can remain confident that the rate of serious side effects – referred to as adverse events – is remarkably low for both types of vaccines,” said Dr Susan Cheng, a cardiologist and public health researcher at the Smidt Heart Institute at Cedars Sinai in Los Angeles, on mRNA and non-mRNA vaccines.

“That said, while the rates of these adverse events remain extremely low,” she said, “they are important and need to be counted and analyzed so that we can better understand them.”

^{Translated by Luiz Roberto M. Gonçalves}