Icelandic vaccine study (Eythorsson et al.) show probability of reinfection higher in persons who had received 2 or more doses compared with 1 dose or less of vaccine (OR, 1.42; 95% CI, 1.13-1.78)

‘In total, 11 536 PCR-positive persons were included. The mean (SD) age was 34 (19) years (median, 31 years; range, 0-102 years), 5888 (51%) were male, 2942 (25.5%) had received at least 1 dose of vaccine, and the mean (SD) time from initial infection was 287 (191) days (median, 227 days; range, 60-642 days). Reinfection was observed in 1327 persons (11.5%) during the Omicron period.

The probability of reinfection increased with time from the initial infection (odds ratio of 18 months vs 3 months, 1.56; 95% CI, 1.18-2.08) (Figure) and was higher among persons who had received 2 or more doses compared with 1 dose or less of vaccine (odds ratio, 1.42; 95% CI, 1.13-1.78). Defining reinfection after 30 or more days or 90 or more days did not qualitatively change the results.’

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