SARS-CoV-2 re-infection risk in Austria

Area of Science:

• Epidemiology
• Immunology
• Public Health

Background:

• Assessing the duration and effectiveness of natural immunity following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is crucial for understanding coronavirus disease 2019 (COVID-19) epidemiology.
• Evaluating the risk of SARS-CoV-2 reinfection in a general population is essential for informing public health strategies.

Purpose of the Study:

• To evaluate the risk of SARS-CoV-2 reinfection in individuals who previously had COVID-19.
• To compare the odds of reinfection in first-wave survivors with the odds of primary infection in the general population during the second wave in Austria.

Main Methods:

• A retrospective observational study utilizing national SARS-CoV-2 infection data from Austria's epidemiological reporting system.
• Comparison of polymerase chain reaction (PCR)-confirmed infections between COVID-19 survivors from the first wave (Feb-Apr 2020) and the general population during the second wave (Sep-Nov 2020).

Main Results:

• A total of 40 tentative SARS-CoV-2 reinfections were recorded among 14,840 COVID-19 survivors (0.27%).
• In comparison, 253,581 primary infections occurred in 8,885,640 individuals in the general population (2.85%).
• The odds ratio for reinfection was 0.09 (95% CI: 0.07 to 0.13), indicating significantly lower odds of reinfection in previously infected individuals.

Conclusions:

• A low rate of SARS-CoV-2 reinfection was observed in Austria.
• Natural immunity following COVID-19 infection provides protection comparable to high vaccine efficacies.
• Further research is needed to guide public health measures and vaccination strategies effectively.