EU Regulator: AstraZeneca Vaccine Effective, Blood Clots May Be A Rare Side Effect

The European Union's drug regulator said Wednesday that the benefits of AstraZeneca's COVID-19 vaccine outweigh its risks, but that very rare blood clotting events should be listed as a possible side effect.

The European Medicines Agency's assessment comes after a panel of experts reviewed reports of unusual blood clots occurring in some vaccine recipients. Officials stressed that these events are very rare, and said that while they appear to be more common in women under the age of 60, there is not enough available evidence to confirm specific risk factors such as age, gender or previous medical history.

They said it is important for healthcare providers and the public to be aware of the signs and symptoms of these unusual events — which include shortness of breath, persistent abdominal pain and leg swelling — and that the vaccine's product information will be updated to list them as a possible adverse reaction. They are still recommending its use, and emphasized the vaccine has been proven to prevent severe disease, hospitalizations and deaths.

"The risk of mortality from COVID is much greater than the risk of mortality from these side effects," said Emer Cooke, executive director of the EMA. " I think it's important that we give the message that vaccines will help us in the fight against COVID and we need to continue to use these vaccines."

Last month, reports emerged of dozens of blood clots occurring after vaccination, several of them fatal. That prompted more than a dozen countries, mostly in Europe, to temporarily suspend use of the AstraZeneca vaccine, though the EMA and World Health Organization both continued to recommend its use.

Many of those countries resumed inoculations after an EMA investigation last month found that the vaccine's benefits far outweigh its risks, with officials pointing out that the number of "thromboembolic events" reported after vaccination was actually lower than expected in the general population.

The regulator announced on March 18 that its preliminary investigation had determined the vaccine to be safe and effective, and said there is no increase in the overall risk of blood clots associated with its use, even as some questions remained.

Several of the countries to resume AstraZeneca vaccinations have done so with conditions; for example, French health authorities are recommending it only for people ages 55 and older, Germany suspended the "routine use" of the vaccine for people under 60 and South Korea said Wednesday it will temporarily withhold the vaccine from people under 60.

And on Tuesday, the University of Oxford announced it was pausing a small trial in the U.K. that would test the vaccine on individuals ages six to 17 as it waited for more data on the blood clotting reports.

The AstraZeneca vaccine has been approved by many countries across the world, and its affordability — at just $4 a dose — and minimal handling requirements make it ideal for global use, as NPR has reported.

The WHO in February approved the vaccine for emergency use to be rolled out globally through COVAX, an international effort to help low- and middle-income countries combat the pandemic. And the Biden administration said last month it was finalizing plans to loan millions of doses to Mexico and Canada.

It is not currently being used in the U.S. The company has said it will seek emergency use authorization from the U.S. Food and Drug Administration, which would make it the fourth coronavirus vaccine available in the country.

That process has also raised some questions, after an independent monitoring board said the company released data showing an incomplete picture of its efficacy. AstraZeneca then published results showing slightly diminished efficacy figures: 76% effective against symptomatic COVID-19 and 100% effective against severe or critical disease and hospitalization.

Dr. Anthony Fauci, the Biden administration's chief medical adviser, told Reuters earlier this month that the U.S. may not need it in order to vaccinate the entire population.

"My general feeling is that given the contractual relationships that we have with a number of companies, that we have enough vaccine to fulfill all of our needs without invoking AstraZeneca," he said. [Copyright 2021 NPR]