Coronavirus prevalence remains high due to a new Omicron subtype and a declining sense of danger

The results of the November wave of the University of Tartu-led coronavirus prevalence study show that the virus spread remains consistently high for the fourth month. The same can be said about antibody prevalence. The wide spread of the virus is driven by the more infectious Omicron subtype on the one hand and by people's declining sense of danger on the other.

The chart shows the comparative overview of the results of 31 study waves. Source: University of Tartu

During the survey wave from 15 to 28 November, 1,970 people were tested for coronavirus. 5.8% of them tested positive, with 3.7% (one in 27 adults) still infectious. Of the infectious, 80% had either mild or moderate symptoms. According to Ruth Kalda, head of the prevalence study and Professor of Family Medicine at the University of Tartu, these figures have been more or less the same since the end of August. The persistence of high infection rates is partly due to the Omicron subtype BQ1.1, which was already noticed during the previous survey wave and has gained a strong foothold in Estonia. It has caused as many as a fifth of the cases detected in the current wave. "This is an even more contagious than the previous Omicron strain, and can bypass the immune response of previous infections. Fortunately, the cases caused by this strain also tend to be mild, and it usually does not cause severe disease," Kalda explained.

In this study wave, 1,855 people provided samples for antibody analysis, and 90% of them had antibodies. Among people over 65, antibody prevalence was 95%. This study wave showed that while almost all vaccinated people have antibodies, only 66% of those who have not been vaccinated but have recovered from the disease have antibodies. Again, the data confirm that people who have received two booster doses have significantly more antibodies than others. They also have slightly fewer cases of infection. While 15% of respondents in the younger age group would like to get the booster dose, a third of those over 65 are planning to get it. Ruth Kalda strongly recommends that all older people and all people in high-risk groups with underlying diseases get the booster dose.

A behavioural survey carried out during the study again showed that the general sense of danger has decreased. Even though one in ten adults has had close contact with a potentially infected person, only one in five have taken action to contain the spread of infection. According to Kalda, people tend to forget that coronavirus is an infectious disease. She reminded people again that the easiest way to avoid contracting the virus and spreading the infection is to take the usual precautions: wash your hands, take a rapid test even with mild symptoms and avoid close contact if you show any signs of the virus.

The study on the prevalence of coronavirus is carried out by a broad-based research group of the University of Tartu in cooperation with Synlab Eesti, Medicum and Kantar Emor.

The prevalence study is the only tool in Estonia to monitor the prevalence of the coronavirus in adult population. The findings will help decision-makers to make evidence-based decisions on the use of healthcare resources for the health and well-being of Estonian citizens. The study is commissioned by the Government of the Republic and funded by the European Regional Development Fund from the EU measure to respond to the Covid-19 pandemic.

For more information about the study, see the University of Tartu web page.

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