The majority of people who were likely infected with the Omicron variant of SARS-CoV-2, the virus that causes Covid-19, did not know they had the virus, according to a new study.
Researchers from Smidt Heart Institute at Cedars-Sinai included 2,479 people who had contributed blood samples just prior to or after the start of the Omicron surge. They identified 210 people who likely were infected with the Omicron variant based on newly positive levels of antibodies to SARS-CoV-2 in their blood.
The findings, published in JAMA Network Open, showed that only 44 per cent of participants with newly positive SARS-CoV-2 antibodies had awareness of being infected with the virus. The majority (56 per cent) were unaware of any recent Covid-19 infection.
Of the study participants who were unaware, only 10 per cent reported having any recent symptoms that they attributed to a common cold or other type of infection.
"More than one in every two people who were infected with Omicron didn't know they had it," said Susan Cheng, director of the Institute for Research on Healthy Aging in the Department of Cardiology at the Institute.
"Awareness will be key for allowing us to move beyond this pandemic," she added.
Prior studies have estimated that at least 25 per cent and possibly as many as 80 per cent of people infected with SARS-CoV-2 may not experience symptoms. Compared to other SARS-CoV-2 variants, the Omicron variant is associated with generally less severe symptoms that may include fatigue, cough, headache, sore throat or a runny nose.
"Our study findings add to evidence that undiagnosed infections can increase transmission of the virus," said Sandy Y. Joung, from Cedars-Sinai. "A low level of infection awareness has likely contributed to the fast spread of Omicron."
More studies involving larger numbers of people from diverse ethnicities and communities are needed to learn what specific factors are associated with a lack of infection awareness, according to the investigators.
"We hope people will read these findings and think, aI 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.' The better we understand our own risks, the better we will be at protecting the health of the public as well as ourselves," said Cheng.