“More than one out of every two people infected with Omicron do not know they have it,” said Susan Cheng, MD, PhD, director of the Healthy Aging Institute, Division of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center. and the corresponding author of the study. “Awareness will be the key to getting us beyond this pandemic.”
Previous studies have estimated that at least 25%, and possibly as many as 80% of people infected with SARS-CoV-2 may experience no symptoms. Symptoms of the Omicron variant are generally less severe than those of other SARS-CoV-2 variants and may include fatigue, headache, cough, sore throat or runny nose.
“Our findings add to the evidence that undiagnosed infections can increase viral transmission,” said Sandy Y. Joung, an investigator at Cedars-Sinai Medical Center and the study’s lead author. “Low levels of infection awareness may have contributed to the rapid spread of Omicron.”
Investigators began collecting blood samples from health care workers more than two years ago as part of a study into the impact of COVID-19 and the impact of a vaccine. In the fall of 2021, just before the surge in Omicron variant infections began, investigators were able to expand recruitment to include patients thanks to the research infrastructure and biospecimen processing support provided by Sapient Bioanalytics.
Of the health care workers and patients who participated in the study, the researchers found 2,479 who provided blood samples before or after the onset of Omicron infection cases. Investigators determined that 210 people may have been infected with the Omicron variant, based on the newly positive levels of SARS-CoV-2 antibodies in their blood.
Next, the investigators invited study participants to provide updated health status through interviews and surveys. Of the new SARS-CoV-2 antibody-positive study participants, only 44% knew they had the virus. The majority (56%) were unaware of any recent COVID-19 infection. Of those who didn’t know, only 10 percent reported recent symptoms that they attributed to the common cold or other type of infection.
According to the researchers, more research involving people of different ethnicities and communities is needed to understand which specific factors are associated with a lack of infection awareness.
“We want people to read these studies and think, ‘I just went to a party and someone tested positive’; or, ‘I’m just starting to think the weather is a little bit bad. Maybe I should do a quick test’. We The more we understand our own risks, the better we can protect the public and our own health,” said Erika J. Glazer, chair of women’s cardiovascular health and population sciences at Cedars-Sinai Medical Center.
Susan and her colleagues are also investigating patterns and predictors of reinfection, as well as their potential to provide long-term immunity against SARS-CoV-2. In addition to raising awareness, this information can help people manage their personal risks.