In a sample, the Public Health Authority studied 1,676 people in Stockholm County with confirmed covid-19 who became ill on March 21-30. At the same time, it has been calculated how many unverified cases of illness may have existed and made comparisons with the Swedish Tax Agency's death register.

The study shows that in the group 70 years and older, the mortality rate was 4.3 percent, while that of persons younger than 70 years was 0.1 percent. The figure for the whole group was 0.6 percent.

According to the Public Health Authority, knowledge of how large the proportion of infected people die (lethality) is important for assessing the consequences of the pandemic.

"Just as the rate of dissemination is an important parameter," says Martin Berlin, investigator at the unit for analysis and author of the report.

"Biggest source of uncertainty"

The Public Health Authority defines coronary deaths as those reported to have passed away by a treating physician, through health care or through the regional infection control, as well as people who die within 30 days from the date they were sampled.

On its website, the authority refers to the World Health Organization WHO and studies that estimate mortality globally to 1-2 percent. On the other hand, the experience is that there is extensive under-reporting of new diseases and Martin Berlin says that the few studies that have been published internationally point to the same results as the Public Health Agency's study - around 0.6–0.7 per cent mortality.

-The biggest source of uncertainty is the number of infected, because we do not know for sure how many people are infected overall. But we think that is the best estimate you can get.

Many at elderly homes

The mortality rate depends on who is affected by the virus. The Public Health Authority study shows what is already known, that a large proportion, as many as 37 percent, of the deceased lived in elderly homes. This indicates that mortality could be slightly higher in Stockholm than in the rest of the country where the infection has been kept away from elderly housing to a greater extent.