The majority of people who were likely infected with the Omicron variant were unaware they had the virus, according to a new study published in JAMA Network Open.
“More than one in every two people who were infected with Omicron didn’t know they had it,” said Susan Cheng, MD, MPH, corresponding author of the study. “Awareness will be key for allowing us to move beyond this pandemic.”
Previous work estimated that between 25% and 80% of people infected with SARS-CoV-2 may be asymptomatic. Compared to other variants, Omicron 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, MHDS, an investigator at Cedars-Sinai and first author of the study. “A low level of infection awareness has likely contributed to the fast spread of Omicron.”
As part of research into the effects of COVID and the impact of vaccines, the investigators began collecting blood samples from healthcare workers more than two years ago. In the second half of 2021, just before the start of the Omicron variant surge, the investigators were able to expand enrolment to include patients. Of the healthcare workers and patients who have participated in the research, investigators identified 2479 people who had contributed blood samples just prior to or after the start of the Omicron surge. The investigators identified 210 people who likely were infected with the Omicron variant based on newly positive levels of SARS-CoV-2 antibodies.
Study participants were invited to provide health status updates through surveys and interviews. Only 44% of study participants testing positive were aware of their infection. Of the 56% of study participants who were unaware, only 10% reported having any recent symptoms that they attributed to a common cold or other type of infection.
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.
Cheng and colleagues are also studying patterns and predictors of reinfections and their potential to offer long-lasting immunity to SARS-CoV-2. In addition to raising awareness, this information could help people manage their individual risk.
Source: Cedars-Sinai
