Table 1. Severity of SARS-CoV-2 Reinfections as Compared with Primary Infections in the Population of Qatar.

Disease Outcome*	Reinfection†	Primary Infection†	Odds Ratio (95% CI)
	no. of persons with outcome/no. of persons with infection that was not severe, critical, or fatal
Severe disease	4/1300	158/6095	0.12 (0.03–0.31)
Critical disease	0/1300	28/6095	0.00 (0.00–0.64)
Fatal disease	0/1300	7/6095	0.00 (0.00–2.57)
Severe, critical, or fatal disease	4/1300	193/6095	0.10 (0.03–0.25)

^*Severe disease, critical disease, and fatal disease were defined on the basis of the World Health Organization criteria for classifying severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection severity and coronavirus disease 2019 (Covid-19)–related death.

^†Reinfections were matched with up to five primary infections according to sex, 5-year age group, nationality, and calendar week of polymerase-chain-reaction testing. The final sample therefore includes persons with reinfection who were matched to five or fewer persons with primary infection.