More than half of people—56%—who are infected with the Omicron variant are not aware of their infection.
That’s the conclusion of a small study published on Aug. 17 in JAMA Network Open. It’s good news, in some ways, since it underscores the fact that Omicron tends to cause relatively mild symptoms (or no symptoms at all) in vaccinated people. However, the downside to this is likely that unintentional transmission of Omicron virus occurs.
Dr. Susan Cheng, director of the Institute for Research on Healthy Aging at the Cedars-Sinai Smidt Heart Institute, and her colleagues at the University of California, Los Angeles and Abbott Laboratories, studied 210 employees and patients at Cedars-Sinai who provided at least two blood samples for antibody testing—one before the Omicron surge and one after. These blood samples were then tested for antibodies to SARS-CoV-2 viruses by the researchers.
All of the participants were immunized. The researchers also measured the levels of both the antibodies that the immune systems made to combat the vaccinations and the ones that it made following infection. All of the participants had to be below certain levels of infection-induced antibodies at the beginning of the study. This indicated that they hadn’t been recently infected by the virus. In this way, an increase in antibody levels was used as a marker for infection. Participants completed health questionnaires that described their symptoms, and included COVID-19-PCR testing. This was done to establish if there had been an infection.
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According to the researchers, 56% of those who had tested positive did not realize they had contracted the disease. They either didn’t feel any symptoms or thought it was a flu-like illness. According to early evidence from the rest of the world, the majority of SARS/CoV-2 cases were asymptomatic. Public-health officials are faced with challenges in trying to curb the epidemic.
“If one message comes out of our study, I hope it’s that awareness of your infection status is going to be really key to get us through this pandemic faster,” says Cheng. “Lack of awareness and lack of knowing could lead to walking around with something transmissible, and unwittingly passing the virus to a household member, neighbor, co-worker, or someone at the grocery store.”
The data showed that people’s awareness of their infection status improved after at-home rapid test kits became widely available earlier in 2022. About 75% were not aware of their infection when they were tested in February and January, but only 56% knew by May.
The fact that one out of two people infected with Omicron aren’t even aware that they have COVID-19 makes a strong case for more frequent testing. Regularly testing yourself with at-home rapid antigen kits is a good idea even if you don’t feel sick, since transportation, work, school, and crowded public venues—like for concerts or sports games—are all places where you can potentially get infected.
Chen believes that knowing your current infection status is important because studies have demonstrated that Omicron Subvariants can be infected multiple times. To better understand the risk factors and how often people get multiple infections, Chen is studying reinfection.
“Increasing people’s awareness of their status is our goal,” she says. “Unfortunately, we have to live with this virus for some time, and if we can be more aware, then we can potentially help ourselves, our families, and our communities to curb the spread of the virus.”
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