Study: Many people unaware they're infected may be spreading COVID-19

A majority of people infected with COVID-19's Omicron variant may be unaware they have the highly contagious virus, which likely contributes to its rapid spread, new research suggests. File Photo by Peter Foley/UPI | <a href="/News_Photos/lp/85b4fdf0ce2928dd3e760b1768ace9ba/" target="_blank">License Photo</a>
A majority of people infected with COVID-19's Omicron variant may be unaware they have the highly contagious virus, which likely contributes to its rapid spread, new research suggests. File Photo by Peter Foley/UPI | License Photo

Aug. 17 (UPI) -- More than half of the people infected with COVID-19's Omicron variant were unaware they had the highly contagious virus, and this may be a "key contributor" to its rapid person-to-person transmission within communities, a new study says.

Researchers found that 56% of 210 adult patients and employees with recent Omicron variant infection who participated in the study at Cedars-Sinai Medical Center in Los Angeles reported being unaware they were infected.


And while awareness of infection was higher among Cedars-Sinai's healthcare employees than others in the study, such awareness remained low.

The research findings were published Wednesday in JAMA Network Open.

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Given that some people infected with the Omicron variant were unaware of their infectious status while the virus was actively transmissible, the investigators urged people to remain cautious.

"People want to think of COVID as being like the common cold, but in some people it can cause no symptoms while in others it can lead to hospitalization," Susan Cheng, the study's corresponding author, told UPI in an email.


"Although people might be ready for the pandemic to be over, caution is still needed."

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Yet, Cheng, director of the Institute for Research on Healthy Aging in the Department of Cardiology at Cedars-Sinai's Smidt Heart Institute, said the level of healthcare workers' still low awareness of omicron infection is not especially concerning.

"In the healthcare work environment, everyone is masked, making transmission less likely than in most other types of environments," she said.

Asked whether the research findings suggest more training or frequent testing of healthcare workers is needed, Cheng replied: "We already have rigorous protocol[s] for screening and testing of employees, as well as very generous employer coverage for people who test positive."

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The study's participants had 2 or more serial anti-nucleocapsidIgG (IgG-N) antibody measurements at least 1 month apart, the research paper said.

The first test was performed after the end of a regional Delta variant surge, on Sept. 15, 2021; and a subsequent test occurred after the start of a regional Omicron variant surge, on Dec. 15, 2021.

Adults with evidence of new SARS-CoV-2 infection occurring during the Omicron variant surge period through May 4, 2022, were included in the study sample, the researchers said.

The study participants' awareness of recent infection was determined from review of self-reported health updates, medical records, and COVID-19 testing data.


Individuals aware of their recent Omicron infections were more likely to be younger, as well as more likely to be health care employees of Cedars-Sinai, than unaware people.

But both groups were otherwise similar in demographics and in the number of vaccination doses or types of vaccines received.

The participants had a mean age of 51, though the range extended from 23 to 84 years old; and 65% were women. Of the 56% who reported being unaware of their infectious state, 10%, or 12 of 118 people, reported having had any symptoms, which they attributed to a common cold or other non-COVID infection.

Further analyses that accounted for demographic and clinical characteristics indicated that participants who were the medical center's workers were more likely than non-employees to be aware of their recent Omicron variant infection.

Despite all of the known factors in the Omicron variant surge, the investigators said there remained unknown variables, especially including the extent to which infected individuals may be unaware of their ability to spread the virus.

The researchers said multiple previous studies have indicated that asymptomatic or minimally symptomatic COVID infections are likely triggers of outbreaks.

And, despite the wide availability of at-home rapid antigen testing kits, the extent to which some infected individuals don't realize they're able to actively transmit the virus has remained an unknown.


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