Is The AstraZeneca Coronavirus Vaccine Safe? Here's What To Know.

The shot is linked to reports of blood clots and lower efficacy against COVID-19 variants, but there's more that everyone needs to understand.
Experts weigh in on the safety and efficacy of AstraZeneca's COVID-19 vaccine.
Dan Kitwood via Getty Images
Experts weigh in on the safety and efficacy of AstraZeneca's COVID-19 vaccine.

AstraZeneca’s COVID-19 vaccine has taken some heat lately. In March, over a dozen countries decided to temporarily stop administering the shot after a handful of people experienced blood clots. Soon after, a report came out claiming the AstraZeneca vaccine is only 10.4% effective against cases caused by the B.1.351 variant first detected in South Africa.

But many infectious disease experts stand behind AstraZeneca’s vaccine, and they say headlines about the shot’s issues haven’t necessarily told the full story. Health officials believe the vaccine is safe and effective — and that it has the power to help us drive down cases globally and win back some control over the coronavirus pandemic.

Here’s what to know about the AstraZeneca vaccine:

AstraZeneca’s shot is still ruled safe and effective right now.

The European Medicines Agency investigated cases of blood clots in March and ruled that the vaccine was safe and effective. However, warning was added to the product, according to The Washington Post.

In April, the EMA found that the vaccine can, in rare cases, cause blood clots with low blood platelets. The most recent data from the United Kingdom shows that 79 people in the country have experienced blood clots after receiving the vaccine. Nineteen people have died. That risk is equivalent to four in 1 million people. The majority of those affected were women.

This prompted the U.K. government’s vaccine advisory group to recommend that those ages 18 to 29 are offered a Pfizer or Moderna COVID-19 vaccine when available. People with blood disorders or other illnesses that leave them at risk for clotting should also speak with their doctors before getting the AstraZeneca shot, the BBC reported.

All that said, the EMA still stresses that the benefits of the vaccine overall still outweigh the low risk of blood clots. While the link between the AstraZeneca vaccine and blood clots appears to be getting firmer, specific risk factors for this issue have yet to be confirmed, according to the EMA. For the vast majority of people, the vaccine is still recommended.

And, for what it’s worth, getting COVID-19 is also known to cause severe clotting in some people.

The shot appears to prevent COVID-19 hospitalization and death.

A clinical trial published in March in the New England Journal of Medicine found that the overall efficacy of the AstraZeneca shot dropped to 10.4% when tested against the B.1.351 variant first identified in South Africa. Overall, the shot is 76% effective at preventing disease.

It’s true that some vaccinated people contracted mild to moderate cases of COVID-19, but no vaccinated individuals died or were hospitalized.

“The whole reason we care about vaccines ― the biggest goal for the vaccines ― is to prevent three things: severe illness, hospitalization and death,” Amesh Adalja, a senior scholar at the Johns Hopkins University Center for Health Security and an infectious disease expert, told HuffPost in March.

Whenever there’s a claim that a vaccine doesn’t hold up against a variant, he recommends skipping over the part about mild to moderate illness and looking instead for the data about serious disease, hospitalizations and death.

“I’m much more focused on the whole reason we care about COVID-19 and why we don’t care about many other coronaviruses, which is that this one causes severe disease,” Adalja said.

Monica Gandhi, an infectious diseases specialist and professor of medicine at the University of California, San Francisco, agreed. It’s disappointing the AstraZeneca vaccine’s efficacy dipped against mild to moderate illness, but she said it’s much more important to look at the shot’s efficacy against severe disease.

“All of the vaccines — including AstraZeneca and including when tested against variants — are effective to prevent severe disease, which is what we fear the most,” Gandhi said in March.

So overall, what do experts really think about the shot?

It’s fair that there’s some hesitation given the news around this particular vaccine.

But, overall, “this is a safe and efficacious vaccine and it’s a main driver of the control the United Kingdom is having right now,” Adalja said.

If you aren’t convinced by the clinical trials, look at the real-world data. In the U.K., where the AstraZeneca vaccine has been widely administered, hospitalizations are plummeting. In Scotland, evidence shows just one dose of the AstraZeneca vaccine cuts the risk of hospitalization by 94%. A clear trend is emerging: The countries that are vaccinating people the fastest are seeing the biggest dips in cases, and more importantly, hospitalizations.

Even a partially effective vaccine, like the AstraZeneca shot, will be able to save lives and slow the spread of COVID-19.

“We are seeing astounding results,” Gandhi said. “The real-world data for the AstraZeneca vaccine is very exciting.”

This story has been updated with new information on the reports of blood clots following the AstraZeneca vaccine.

Experts are still learning about COVID-19. The information in this story is what was known or available as of publication, but guidance can change as scientists discover more about the virus. Please check the Centers for Disease Control and Prevention for the most updated recommendations.


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