Study: 56% of Omicron-infected adults didn't know they were contagious

An observational study of 210 adults in California with detectable SARS-CoV-2 antibodies during an Omicron variant wave shows that 56% didn't know they had been infected, fueling concerns about asymptomatic transmission, according to a report today in JAMA Network Open.Researchers at Cedars-Sinai Medical Center led the study of adult employees and patients of the hospital in Los Angeles County who had at least two SARS-CoV-2 antibody tests 1 month or more apart.

The first test occurred after the Delta variant surge on Sep 15, 2021, and the second was conducted amid the Omicron wave from Dec 15, 2021, to May 4, 2022.

Participants also completed surveys on vaccinations, viral exposures, and symptoms at baseline and throughout the study.The investigators called the study the first to assess Omicron infection awareness, which is key to timely self-isolation, in a diverse urban area in the United States.10% had symptoms ascribed to cold, other illnessAmong the 210 participants, median age was 51 years, 65% were women, 44% knew they had a recent Omicron infection, and 56% said they didn't know they were infected.

Of the 118 participants who were unaware of their infection, 12 (10%) said they had symptoms but had attributed them to a common cold or other non-COVID infection.A multivariable analyses showed that overall awareness was low but that center employees were more likely than patients to know they were infected (adjusted odds ratio [aOR], 2.46)."This finding may be explained not only by the differences in general health awareness and literacy between employees and nonemployees but also by the mandatory daily screening protocols for employees that are supported by COVID-19 sick pay policies, which were broadened at the