SARS‐CoV‐2 re‐infection risk in Austria

Abstract

Background A key question concerning coronavirus disease 2019 (COVID‐19) is how effective and long lasting immunity against this disease is in individuals who were previously infected with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). We aimed to evaluate the risk of SARS‐CoV‐2 re‐infections in the general population in Austria. Methods This is a retrospective observational study using national SARS‐CoV‐2 infection data from the Austrian epidemiological reporting system. As the primary outcome, we aim to compare the odds of SARS‐CoV‐2 re‐infections of COVID‐19 survivors of the first wave (February to April 30, 2020) versus the odds of first infections in the remainder general population by tracking polymerase chain reaction (PCR)‐confirmed infections of both groups during the second wave from September 1 to November 30, 2020. Re‐infection counts are tentative, since it cannot be excluded that the positive PCR in the first and/or second wave might have been a false positive. Results We recorded 40 tentative re‐infections in 14 840 COVID‐19 survivors of the first wave (0.27%) and 253 581 infections in 8 885 640 individuals of the remaining general population (2.85%) translating into an odds ratio (95% confidence interval) of 0.09 (0.07 to 0.13). Conclusions We observed a relatively low re‐infection rate of SARS‐CoV‐2 in Austria. Protection against SARS‐CoV‐2 after natural infection is comparable with the highest available estimates on vaccine efficacies. Further well‐designed research on this issue is urgently needed for improving evidence‐based decisions on public health measures and vaccination strategies.

Antibodies Responses to SARS-CoV-2 in a Large Cohort of Vaccinated Subjects and Seropositive Patients

“…Thus, infection and the development of an antibody response could provide similar or even better protection than do the currently used SARS-CoV-2 vaccines, although antibody responses induced by SARS-CoV-2 infection are often lower in titers than those induced by vaccination. In this sense, several other studies demonstrated that infection does protect against reinfection, probably in an antibody-dependent manner [ 32 , 33 , 34 , 35 ].…”

Serum antibody response to BNT162b2 after natural SARS‐CoV‐2 infection

“…A further indicator for the protective effect of a natural SARS‐CoV‐2 infection is the low observed rate of reinfections. 17 , 21 , 22 Individuals who underwent SARS‐CoV‐2 infection are thus generally considered immune for at least a few months. It could therefore, be hypothesized that a single bout of a SARS‐CoV‐2 vaccine might be sufficient for consolidating this protective immunity.…”

COVID-19 vaccination: the reality after clinical trials

“…En un estudio observacional retrospectivo, realizado en la población de Austria, se selecciona a las personas que padecieron COVID-19 en la primera oleada y lo sobrevivieron (febrero a abril de 2020) y se compara el riesgo de padecer COVID-19 durante el periodo que va desde el 1 de septiembre al 30 de noviembre de 2020. Se registraron 40 reinfecciones en 14.840 supervivientes del COVID-19 de la primera oleada (0,27%) y 253.581 infecciones en 8.885.640 individuos del resto de la población general (2,85%) [3]. Esto es concordante con el hecho de que la mayoría de pacientes que han pasado la infección mantienen al menos 6 meses la presencia de anticuerpos anti-SARS-CoV-2 IgG y neutralizantes.…”