Largest Seroprevalence Study in US Shows Vast COVID-19 Undercount

Actual cases may be as much as 6 to 24 times higher than reported, but we’re still a long way off from herd immunity.

Written byAmanda Heidt

| 3 min read

COVID-19, SARS-CoV-2, coronavirus, pandemic, antibodies, seroprevalence, CDC, antibody, testing

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The number of COVID-19 infections nationwide is 6 to 24 times higher than the 3.9 million confirmed cases, according to new data from the US Centers for Disease Control and Prevention.

The results of the new study, published this week (July 21) in JAMA Internal Medicine by CDC researchers and state health officials, represent the largest antibody survey of its kind. Even accounting for these hidden cases detected in 10 cities across the US, the findings suggest that many of the cities are nowhere near the antibody prevalence required for herd immunity. Additionally, scientists are unsure just how long people retain their antibodies after being infected, and what that means for immunity to the disease.

“These data continue to show that the number of people who have been infected with the virus that causes Covid-19 far exceeds the number of reported cases,” Fiona Havers, a CDC ...

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Meet the Author

Amanda Heidt
Amanda first began dabbling in scicom as a master’s student studying marine science at Moss Landing Marine Labs, where she edited the student blog and interned at a local NPR station. She enjoyed that process of demystifying science so much that after receiving her degree in 2019, she went straight into a second master’s program in science communication at the University of California, Santa Cruz. Formerly an intern at The Scientist, Amanda joined the team as a staff reporter and editor in 2021 and oversaw the publication’s internship program, assigned and edited the Foundations, Scientist to Watch, and Short Lit columns, and contributed original reporting across the publication. Amanda’s stories often focus on issues of equity and representation in academia, and she brings this same commitment to DEI to the Science Writers Association of the Rocky Mountains and to the board of the National Association of Science Writers, which she has served on since 2022. She is currently based in the outdoor playground that is Moab, Utah. Read more of her work at www.amandaheidt.com.
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