In Austria, more than 440,000 people tested positive for SARS-CoV-2 by Feb. 21, 2021. For the first time, AGES, the Medical University of Graz and Stanford University have conducted a study in Austria to determine the extent to which these people are protected against re-infection with SARS-CoV-2. Result: The risk of becoming infected with SARS-CoV-2 again after passing through infection is 91 percent lower than the risk of becoming infected with SARS-CoV-2 for the first time.
From September to November 2020, individuals infected with SARS-CoV-2 during the first wave of infection (February to April 2020) were compared with the rest of the Austrian general population. During this study, re-infections with SARS-CoV-2 were detected in 40 individuals.
Within approximately seven months of the initial infection, individuals with a history of SARS-CoV-2 infection had a 91% lower risk of re-infection compared to the general population. This result suggests that one has similar protection against re-infection after SARS-CoV-2 infection as after vaccination.
This publication is the first to present the true risk of re-infection in the entire population of a country, including all age groups. Previous studies of immunity were based on antibody determinations in specific study populations. The data show an emerging immunity against SARS-CoV-2 in the Austrian population. However, it is not yet possible to say to what extent this immunity can also be applied to various SARS-CoV-2 virus mutations or how long and to what extent this re-infection protection lasts over longer periods of time. Further evaluation of the risk of re-infection over longer periods of time, as well as data from other countries, is therefore urgently needed.
ORIGINAL PAPER
Stefan Pilz, Ali Chakeri, John PA Loannidis, Lukas Richter, Verena Theiler-Schwetz, Christian Trummer, Robert Krause, Franz Allerberger: SARS-CoV-2 re-infection risk in Austria (First published: 13 February 2021, https://doi.org/10.1111/eci.13520), https://onlinelibrary.wiley.com/doi/abs/10.1111/eci.13520