A new study by AGES experts in cooperation with the Medical University of Graz and international scientists shows that COVID-19 vaccinations were also beneficial for people who had already been infected with the virus. Infection data from the electronic reporting system (EMS) of the "Delta wave" 2021 and the "Omikron wave" 2022 in Austria were analysed. The study analysed data from almost 500,000 previously infected people. The research team wanted to know whether and how well one or two vaccine doses protect against new infections and deaths from COVID-19.

Lower risk of re-infection

The result: vaccinated people had a lower risk of re-infection. In the study, unvaccinated people re-infected almost ten times as often as vaccinated people. This protection decreased significantly over the course of six months. It should be emphasised that the risk of dying from a new infection was very low for people who were already infected, regardless of whether they had been vaccinated or not. During the study period, 17 COVID-19 deaths after reinfection were documented, of which 6 were vaccinated and 11 unvaccinated people. The already low risk of dying from a SARS-CoV-2 reinfection was further reduced by the vaccination.

The study thus emphasises the importance of vaccination, even for people who have already been infected, even if the protection wears off over time.

The study is available at: Alena Chalupka, Uwe Riedmann, Lukas Richter, Ali Chakeri, Ziad El-Khatib, Martin Sprenger, Verena Theiler-Schwetz, Christian Trummer, Peter Willeit, Harald Schennach, Bernhard Benka, Dirk Werber, Tracy Beth Høeg, John P A Ioannidis, Stefan Pilz, Effectiveness of the First and Second Severe Acute Respiratory Syndrome Coronavirus 2 Vaccine Dose: A Nationwide Cohort Study From Austria on Hybrid Versus Natural Immunity, Open Forum Infectious Diseases, Volume 11, Issue 10, October 2024, ofae547, https://doi.org/10.1093/ofid/ofae547