New study by Med Uni Graz on COVID-19 vaccination

Sneezing on the bus, coughing on the streetcar, catching a cold at work - a record number of sick notes and wastewater analyses show an unprecedented viral load throughout Austria. The winter, and with it the new COVID-19 wave, has hit Austria hard. The virus, which has been keeping us on our toes since the beginning of 2020, is once again sweeping through the country, even if its progress is to be slowed down with the help of vaccinations and precautionary measures. A new study by the Medical University of Graz in collaboration with the Austrian Agency for Health and Food Safety (AGES) has looked at the effect of the COVID-19 vaccination: What were the benefits of a fourth vaccination dose? Stefan Pilz from the Department of Endocrinology and Diabetology at the Medical University of Graz got to the bottom of this question.

Vaccination as a milestone in the fight against the pandemic

After the start of the pandemic in spring 2020, the first vaccine doses reached Austria in December of the same year. For the first time, in addition to reducing (social) contact and increasing hygiene measures (such as masks and hand washing), there was another way to protect yourself from the virus and take a first step on the road to normality. The vaccinations have confirmed their safety and effectiveness in extensive studies both nationally and internationally, saved many lives and protected many more from serious after-effects such as Long COVID. Vaccine doses number four and five are now being administered with adapted vaccines. Together with AGES, researchers at the Medical University of Graz have now investigated how effective the fourth vaccination was in people who also had a history of SARS-CoV-2 infection.

Four million Austrians analyzed

For this retrospective study, data from the AGES Epidemiological Reporting System (EMS) and the COVID-19 vaccination register were used and analyzed in the period at the end of 2022 and in the first half of 2023. In total, the data of almost four million people, all of whom had already been infected with SARS-CoV-2, were analyzed for the study. The data was analyzed with regard to COVID-19 deaths as well as (new) infections with the virus and how the risk for people changes over time after vaccination. "How effective was the fourth vaccination for people who were already infected with SARS-CoV-2?", says Stefan Pilz, summarizing the main question of the study.

Vaccination in a new phase of the pandemic

"We were able to prove that people with a fourth vaccination have significant protection against infection with SARS-CoV-2, but that this protection has also decreased over time (within about three months)," explain Alena Chalupka and Lukas Richter from AGES. There was no significant effect in terms of COVID-19 mortality, possibly because COVID-19 mortality was already generally at a very low level. Aspects such as a reduction in hospital stays, the general attenuation of symptoms or the prevention of long-term COVID-19 illnesses were not part of the study.

The vaccination has made a major contribution to transforming the pandemic into an endemic phase. As before, evaluations of the SARS-CoV-2 vaccination in terms of efficacy (e.g. prevention of deaths, severe courses and new infections) continue to be carried out.

Many aspects are still open

While the study has provided many answers, it has also raised a number of questions. Among other things, how to interpret the data from unvaccinated people, who tend to be (or have been) tested less often, or which factors (vaccination, natural immunities, treatment options, mutations of the virus) have led to a reduction in mortality over time. These questions need to be answered in the course of further studies and analyses.

Profile: Stefan Pilz

Stefan Pilz is Associate Professor and Head of the Outpatient Clinic for Endocrinology at the Medical University of Graz. In addition to COVID-19, his research work also focuses on clinical epidemiological research in the fields of hormonally induced forms of hypertension and vitamin D and calcium metabolism, which has enabled him to publish numerous high-ranking scientific publications as part of various international collaborations, making him one of the most cited researchers at the Medical University of Graz.