Table 3.

Overview of predictors used in the analysis

Demographic variables
Gender	Binary variable; coded as 1 for women.
Age	Categorical variable for age groups 30–39;40–49;50–59;60–69.
Immigrant	Binary indicator for whether the individual was born in Norway

Socioeconomic variables
Education	The highest level of education achieved during life, divided in 4 categories: Primary education (ISCED-11 levels 1–3), secondary education (ISCED-11 levels 4–5), low university education (ISCED-11 level 6), high university education (ISCED-11 levels 7–8).
Income	Birth cohort- and gender-stratified income quintile, i.e., 5 categories based on the individual annual income.

Health care utilization prior to infection
Primary care consultations	For each chapter in the International Classification of Primary Care (ICPC-2) coding system we created a categorical variable indicating whether the individual had one or more registered consultations in the period 2017–2019.

Vaccination status and virus type
Vaccine	Binary indicator for whether the individual was vaccinated before infection.
Virus type	Wuhan-Hu-1 (hereafter “Wuhan-virus”), Alpha-virus, Delta-virus or Omicron-virus. Coded as a binary indicators based on the month when the individual was infected. The assigned virus type was the dominant type in the month of infection.