The results of the recently completed stage of coronavirus prevalence study led by the University of Tartu show that although the epidemic is gradually receding, the prevalence of the coronavirus is still very high. The percentage of adults with antibodies against coronavirus remains at about 90%. A fifth of those who have recovered from the disease but have not been vaccinated do not have antibodies.
In the study from 30 March to 11 April, 2,296 random-sampled* adult people were tested, and 7.6% of them tested positive. 40% of them were still infectious, while others had recovered from the disease and no longer posed a risk of infection for others.
According to the leader of the prevalence study, the University of Tartu Professor of Family Medicine Ruth Kalda, the percentage of potentially infectious people has decreased by a third compared to March. “We can see that the epidemic is gradually receding but the risk of infection still remains high. In March, one in nine adults was infected, compared to one in thirteen today,” Kalda explained.
The test results show that the infection rate continues to be the lowest among those who have had the disease and have also been vaccinated. Among those who have received the booster dose, infection is 60% lower than among those vaccinated with two doses. According to Kalda, this confirms that vaccination reduces the prevalence of the virus.
Vaccination helps maintain antiviral protection
In this wave of the study, 2,282 people gave blood samples to estimate their coronavirus antibody levels. Nearly 90% of them had developed antibodies. The prevalence of antibodies was the highest in the over-65 age group (94%). Antibodies are present in almost all of those vaccinated, compared to 80% of those who have had the disease.
The survey of past cases of coronavirus showed that among those who had received booster dose, one in four had had the disease, compared to as many as 60% of those who had only completed the basic course of vaccination. These data confirm the importance of booster doses for maintaining protection against coronavirus.
Along with the lifting of restrictions, also people’s sense of threat is disappearing. The study of behaviour revealed a steady increase in the number of people who do nothing to prevent the spread of infection. According to the chief executive of the study, University of Tartu Professor of Public Health Mikk Jürisson, this requires at-risk groups to be more careful to keep themselves safe. “Currently, the infection level is still much higher than at the peak of the autumn wave of infection, which is why unvaccinated and at-risk people should still wear a mask in crowded places, even if masks are no longer mandatory,” Jürisson said.
The prevalence study is carried out by a broad-based research group of the University of Tartu in cooperation with Synlab, Medicum and Kantar Emor. For more information about the coronavirus prevalence study, see the University of Tartu website. The study is funded by the European Regional Development Fund from the EU measure to respond to the Covid-19 pandemic.
* As the sample is stratified by region, age group, gender and education level, the estimation of prevalence is not based on the simple arithmetic mean but the respective weighted mean.