SARS-CoV-2 infections and hospitalizations among immigrants in Norway: significance of occupation, household crowding, education, household income and medical risk. A nationwide register study

Labberton, A. S.; Godoy, A. A.; Elgersma, I. H.; Strand, B. H.; Telle, K.; Arnesen, T. M.; Nygard, K. M.; Indseth, T.

Background: As in other countries, the coronavirus disease 2019 (COVID-19) pandemic has affected Norway's immigrant population disproportionately with significantly higher infection rates and hospitalizations. The reasons for this are uncertain. Methods: Through the national emergency preparedness register, BeredtC19, we have studied laboratory-confirmed infections with SARS-CoV-2 and related hospitalizations in the entire Norwegian population, by birth-country background for the period 15 June 2020 - 31 March 2021, excluding the first-wave due to limited test capacity and restrictive test criteria. Straightforward linkage of individual-level data allowed adjustment for demographics, socioeconomic factors (occupation, household crowding, education, and household income), and underlying medical risk for severe COVID-19 in regression models. Results: The sample comprised 5.49 million persons, of which 0.91 million born outside of Norway, 82 532 confirmed cases, and 3088 hospitalizations. Confirmed infections in this period (per 100 000): foreign-born 3140, Norwegian-born with foreign-born parents 4799, Norwegian-born with Norwegian-born parent(s) 1011. Hospitalizations (per 100 000): foreign-born 147, Norwegian-born with foreign-born parents 47, Norwegian-born with Norwegian-born parent(s) 37. The addition of socioeconomic and medical factors to the base-model (age, sex, municipality of residence) attenuated excess infection rates by 12.0% and hospitalizations by 3.8% among foreign-born, and 10.9% and 46.2% respectively among Norwegian-born with foreign parents, compared to Norwegian-born with Norwegian-born parent(s). Conclusion: There were large differences in infection rates and hospitalizations by country background, and these do not appear to be fully explained by socioeconomic and medical factors. Our results may have implications for health policy, including the targeting of mitigation strategies.