Table 1.

Distribution of individuals with one or more SARS-CoV-2 infections in MSIS and MSIS laboratory database

	30-day interval, n (%)			60-day interval, n (%)			90-day interval, n (%)			180-day interval, n (%)
Total number of infected individuals	768755 (100)			768755 (100)			768755 (100)			768755 (100)
Infected once	744876 (96.9)			747106 (97.2)			748959 (97.4)			754795 (98.2)
Reinfected	23 879 (3.1)			21 649 (2.8)			19 796 (2.6)			13960 (1.8)
One reinfection	23739 (3.1)			21582 (2.8)			19763 (2.6)			13954 (1.8)
Two reinfections	138 (0.02)			66 (0.01)			33 (<0.00)			6 (<0.00)
Three reinfections	2 (<0.00)			1 (<0.00)			-			-
Weeks between 1 and 2 infections, 25, 50 and 75 percentiles	p25	median	p75	p25	median	p75	p25	median	p75	p25	median	p75
Alpha	6	10	18	11	17	24	17	21	29	29	35	51
Delta	20	36	47	27	38	49	30	39	50	35	42	52
Omicron	19	37	51	20	40	53	22	42	54	41	46	59
All variants	18	36	50	20	39	52	22	41	54	40	46	58

Distribution of individuals reported with one or more SARS-CoV-2 infections using 30-, 60-, 90- and 180-days intervals since previous infection, February 2020 to January 2022, Norway (N=768755). The 25^th percentile (p25), median and 75^th percentile (p75) of the number of weeks between first and second infection using 30-, 60-, 90- and 180-days intervals to define reinfections