Mortality in Norway and Sweden during the COVID-19 pandemic 2020-22: A comparative study

• Main Authors: Per-Henrik Zahl (Author), Örjan Hemström (Author), Rune Johansen (Author), Svenn-Erik Mamelund (Author)
• Format: Book
• Published: Elsevier, 2024-04-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 1876-0341; 10.1016/j.jiph.2023.10.033
• Keywords: COVID-19; Excess mortality; Norway; Sweden; Epidemics; Public health; Infectious and parasitic diseases; RC109-216; Public aspects of medicine; RA1-1270
• Source: Journal of Infection and Public Health, Vol 17, Iss 4, Pp 719-726 (2024)

Background: Norway and Sweden picked two different ways to mitigate the dissemination of the SARS-CoV-2 virus. Norway introduced the strictest lockdown in Europe with strict border controls and intense virus tracking of all local outbreaks while Sweden did not. That resulted in 477 COVID-19 deaths (Norway) and 9737 (Sweden) in 2020, respectively. Methods: Weekly number of COVID-19 related deaths and total deaths for 2020-22 were collected as well as weekly number of deaths for 2015-19 which were used as controls when calculating excess mortality. During the first 12-18 months with high rate of virus transmission in the society, excess mortality rates were used as substitute for COVID-19 deaths. When excess mortality rates later turned negative because of mortality displacement, COVID-19 deaths adjusted for bias due to overreporting were used. Results: There were 17521 COVID-19 deaths in Sweden and 4272 in Norway in the study period. The rate ratio (RR) of COVID-19 related deaths in Sweden vs. Norway to the end of week 43, 2022, was 2.11 (95% CI 2.05-2.19). RR of COVID-19 related deaths vs. excess number of deaths were 2.5 (Sweden) and 1.3 (Norway), respectively. RR of COVID-19 deaths in Sweden vs. Norway after adjusting for mortality displacement and lockdown, was 1.35 (95% CI 1.31-1.39), corresponding to saving 2025 life in Norway. If including all deaths in 2022, RR= 1.28 (95% CI 1.24-1.31). Conclusions: Both COVID-19 related mortality and excess mortality rates are biased estimates. When adjusting for bias, mortality differences declined over time to about 30% higher mortality in Sweden after 30 months with pandemics.