Trials Unlikely to Show if COVID-19 Vaccine Prevents Severe Cases

A vaccine expert explains that such answers likely won’t come until a vaccine has already been approved and administered to millions of people.

Written byMax Kozlov

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Nearly 50 vaccines to protect against COVID-19 are speeding through clinical trials at an unprecedented pace. These studies are designed to test the vaccines’ safety and efficacy, but a review published in The Lancet earlier this week (October 27) outlines the challenges in determining whether a vaccine candidate really is efficacious.

The authors of the review note that there are many definitions of efficacious—reducing the likelihood of developing severe symptoms is one, for instance, reducing the number of deaths is another. Presently, the ongoing clinical trials are mainly designed to determine if recipients have a reduced risk of a coronavirus infection, but knowing whether a vaccine can prevent people from developing severe COVID-19 or dying is a long way off. Vaccine developers have not produced evidence of such a benefit yet, rather, a number of them have reported evidence of an immune response in recipients, data that ...

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Meet the Author

Max Kozlov
Max is a science journalist from Boston. Though he studied cognitive neuroscience, he now prefers to write about brains rather than research them. Prior to writing for The Scientist as an editorial intern in late 2020 and early 2021, Max worked at the Museum of Science in Boston, where his favorite part of the job was dressing in a giant bee costume and teaching children about honeybees. He was also a AAAS Mass Media Fellow, where he worked as a science reporter for the St. Louis Post-Dispatch. Read more of his work at www.maxkozlov.com.
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