Disease severity during SARS-COV-2 reinfection: a nationwide study


  • SARS-CoV-2 reinfections are associated with a lower risk of death than first infections.
  • Prior infection and immunization both protect against severe disease at reinfection.
  • Age sex and comorbidities are the main risk factors for illness severity at reinfection.
  • Different results in populations at risk of COVID-19 complication and not at risk.


Deaths reported within 28 days of testing positive were 61% (95% confidence interval: 56% to 65%) lower in suspected COVID-19 reinfection than primary infection cases. In the unvaccinated cohort, reinfections were associated with 49% (37% to 58%) lower odds of hospital admission in cases aged 50 to 65 years in the population not identified at risk of complication for COVID-19, and 34% (17% to 48%) in those at risk. ICU admission at reinfection compared to primary infection decreased 76% (55% to 87%). Individuals at risk and those aged below 50 years, who received at least 1 dose of vaccine against COVID-19, were 62% (39% to 74%) and 58% (24% to 77%) less likely to get admitted to hospital at reinfection, respectively.

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