Sweden had a massive introduction of the virus in February 2020, particularly in Stockholm, and not only from the Alps. During the February winter break, approximately 1 million Swedes travelled abroad, mainly from the Stockholm area. Genome sequencing of COVID-19 virus showed that the virus introduced into Sweden belonged to 3 distinct genetic groups, supporting the hypothesis that there were several separate, parallel introductions early in the pandemic (3).
Up to September 14, 5,846 people have died from COVID-19 in Sweden (2,650 females and 3,196 males) (4). Most deaths have been among individuals over 70 years, and the Stockholm region has been the most affected. Deaths among elderly people in nursing homes represent a high proportion of COVID-19 fatalities. There has been a significant decline in new cases and severe cases during the summer following a peak in late March and early April. Currently, the number of confirmed cases and the ratio of confirmed cases to the number of tests performed has declined, and various assessments show a decline in transmission and numbers of individuals infected. The national incidence of COVID-19 between August 31 and September 6, 2020 was 13 cases per 100,000 inhabitants (4).
There are complex reasons for the high number of fatalities in Sweden compared with neighboring countries, and the impact of several factors needs to be considered when comparing mortality rates. These factors include important differences in the epidemiology of the pandemic and structural differences in demographics and the healthcare system. The management of the pandemic, the role and impact of different response measures, compliance with binding and voluntary measures, and other health effects are also essential considerations for understanding the high number of fatalities.
Population immunity has never been the goal of the Swedish strategy. Immunity has proven to be difficult to estimate due to heterogeneous spread of the virus. The most recent serological survey was conducted in June and showed that 18.7% (95% CI: 14.8%–23.3%) of people living in a highly affected area had antibodies to COVID-19 virus, and that nationwide, approximately 7% of the population had antibodies, with substantial variation by age group and region.