Most people infected with omicron variant ‘didn’t know they had it,’ study finds

Story at a glance


  • Investigators conducting a study examining COVID-19 and the effect of vaccines identified nearly 2,500 blood samples from patients just before and after the start of omicron’s surge.


  • They identified 210 people who likely were infected given antibody levels in their blood.


  • Participant surveys and interviews then found that approximately 44 percent of those whose blood tested positive for virus realized they were infected.


Most people infected by the omicron variant of COVID-19 were not aware they had it, according to a new study.

“More than one in every two people who were infected with omicron didn’t know they had it,” the study’s first author and an investigator at Cedars-Sinai Sandy Y. Joung said in a media release. “Awareness will be key for allowing us to move beyond this pandemic.”

Investigators conducting a study examining COVID-19 and the effect of vaccines identified nearly 2,500 blood samples from patients just before and after the start of omicron’s surge – identifying 210 people who likely had it given antibody levels in their blood.

Participant surveys and interviews then found that approximately 44 percent of those whose blood tested positive for virus realized they were infected.

Only 10 percent of those who said they were unaware of infection reported any COVID-19 symptoms.

The study’s findings are in line with previous studies that have estimated between 25 percent and 80 percent of people infected with the virus may not experience symptoms, the researchers note.

Researchers are hopeful their findings will motivate people to stay vigilant and get tested for the virus when exposed to an infected person.

“We hope people will read these findings and think, ‘I was just at a gathering where someone tested positive,’ or, ‘I just started to feel a little under the weather. Maybe I should get a quick test,’” said the study’s corresponding author Susan Cheng, director of the Institute for Research on Healthy Aging in the Department of Cardiology at the Smidt Heart Institute at Cedars-Sinai.

“The better we understand our own risks, the better we will be at protecting the health of the public as well as ourselves,” Cheng added.

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The Centers for Disease Control and Prevention loosened its COVID-19 guidance late last week. Among other updates, the CDC no longer recommend quarantine periods for those infected, the screening or testing of asymptomatic individuals without known exposures unless they are in high-risk settings.

Slightly more than 67 percent of the total U.S. population is fully vaccinated against COVID-19.

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