Covid-19: the majority of people infected with Omicron did not even know it

What proportion of people who contracted the variant Omicron from SARS-CoV-2 was aware of her infectious state? This is the starting question of researchers from Cedars-Sinai (United States), whose study is published in JAMA Network. More than two years ago, investigators began collecting blood samples from healthcare workers in Los Angeles. at thefall 2021 (just before the start of the Omicron variant push), they included patients to widen the recruitment.

A total of 2,479 participants provided two antibody measurements usable by the researchers: the first after the end of a regional surge of variant Delta and the next after the start of a regional outbreak of the Omicron variant. Of these people, only 210 are likely to have been infected with the Omicron variant. They then provided information on their state of health through surveys and interviews.

The study reveals that only 44% of these people showed that they were aware of a recent infection with the Omicron variant, while 56% of them were unaware.

How to explain this result?

Interestingly, only 10% of study participants who were unaware of their SARS-CoV-2 infection reported having had recent symptoms which they attributed to a cold or another type of illness. infection. On the one hand, this means that the overwhelming majority of participants unaware of their infection were asymptomatic, as is the case for at least 25% of people infected with SARS-CoV-2 according to previous studies.

On the other hand, it shows that because the Omicron variant is associated with generally less severe symptoms — which may include fatigue, cough, headache, sore throat or runny nose — than other SARS-CoV-2 variantsthe link with the virus may be less obvious. There could even be a certain “trivialization” of contamination with the Omicron variant.

Raising awareness to reduce the spread of the virus

” The results of this study suggest that low rates of sensitization to Omicron variant infection may be a key factor in the rapid transmission of the virus within communities. “, report the researchers.

The latter believe that the availability and use of rapid antigen tests should be associated with increased awareness, especially among non-healthcare workers. Indeed, the participants who worked for the Cedars-Sinai Medical Center were more likely to be aware of their recent Omicron infection than non-employees.

However, the study has several limitations, starting with the modest size of the sample, which does not allow detection of the multiple factors associated with ignorance of the infectious status. Since most of the participants were vaccinated with a vaccine at mRNAfurther studies will be needed to find out whether the results would be similar with another type of vaccine or without prior vaccination.