Should You Give the AstraZeneca Vaccine a Shot?

How the risks of the AstraZeneca COVID-19 vaccine stack up against the waiting game.

Is the AstraZeneca vaccine safe? What are the risks?

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Do other COVID-19 vaccines carry the same risk of blood clots?

The story is similar with the Johnson & Johnson vaccine, which, like the AstraZeneca vaccine, is also based on an “old school” adenovirus platform. In the United States, use of the J&J vaccine was paused due to 6 cases of vaccine-related serious blood clots, all of which occurred in women. Currently, the estimated risk of such events is about one in 140,000 in women 18 to 49 years old and one in a million for women 50 and older (see Dear Pandemic article for more information). By contrast, there have been no reports of vaccine-related blood clots with the mRNA COVID-19 vaccines from Pfizer or Moderna.

What risks do I face while waiting for a different vaccine?

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AstraZenica vaccine benefits versus risk of blood clots (ICU admissions over sixteen weeks). Source: Cambridge’s Winton Centre for Risk and Evidence Communication,
Another take on benefits vs risks of the AstraZenica vaccine / Vaxzevria: ICU admissions over sixteen weeks. Source: The European Medicines Agency

How well does the AstraZeneca vaccine prevent COVID-19? Is Pfizer better?

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So… how good is AstraZenica?

In Phase III clinical trials, AstraZeneca reported 75% protection against symptomatic disease and 100% protection against severe disease, with equal or greater efficacy in older adults.

My Bottom Line

My personal risk analysis led me to sign up for AstraZeneca, rather than wait for Pfizer-BioNTech. I got my first dose two days ago, and am feeling very comfortable with my decision, though a bit under the weather. I’m self-monitoring for any blood clot signs over the next few weeks, but am not unduly stressed given their rarity.

Photo by National Cancer Institute on Unsplash


Risk of getting COVID-19

About Me

I’m a scientist and mother of three young children. I completed my PhD in genetics at Stanford and spent the first decade of my career working in cancer research, drug development, and personalized medicine.

Scientist (PhD Genetics @Stanford) * Mother * Passionate about science-based healthy choices * Lifelong learner * Founder: Fueled by Science

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