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The risk of a post-COVID-19 condition is lower after an Omicron infection, after the fourth vaccination and if the person has not developed a post-COVID-19 condition after the first infection. This is revealed by a nationwide survey of around 110,000 participants in the German National Cohort (NAKO Gesundheitsstudie), who were asked to provide information about long-lasting symptoms after a coronavirus infection and their infection and vaccination history.
Figures presented Journal of Infection This shows that the risk of developing post-COVID-19 conditions is decreasing compared to the initial phase of the pandemic.
During the coronavirus pandemic, cases of persistent post-infection symptoms have been reported. The World Health Organization (WHO) refers to new or persistent symptoms 12 weeks after a coronavirus infection that cannot be explained by other causes as a post-COVID-19 condition.
In a recent study, scientists led by University Medicine Halle evaluated information from 109,707 participants in the German National Cohort (NAKO Gesundheitsstudie) about their self-reported health status in relation to post-infection symptoms. The survey was conducted in autumn 2022, looking retrospectively at the pandemic.
At the time of the survey, more than 80% of respondents had received three or more COVID-19 vaccines and 60% reported that they had already been infected with SARS-CoV-2.
In the online questionnaire, researchers asked about 21 possible post-COVID symptoms, such as physical exhaustion, cardiovascular problems and cognitive impairment. About 35% of people who experienced a COVID-19 infection reported at least one persistent COVID-19 symptom four to 12 months after infection. Of those who reported post-COVID symptoms, a quarter reported nine or more symptoms.
Omicron variant has lowest risk of post-COVID-19 complications
The scientists classified the virus variants responsible for a particular infection according to their period of dominance in national surveillance data in Germany. Infections up to December 2020 were classified as wildtype, those between January and June 2021 as the Alpha variant, those between July and December 2021 as the Delta variant, and those from January 2022 as the Omicron variant.
“As our analysis shows, virus variants have an impact on the risk of post-COVID-19 disease. The risk appears to decrease with newer virus variants. Omicron infection was significantly less associated with post-COVID-19 disease than earlier virus variants,” says Professor Dr. Rafał Mikolajczyk, Director of the Institute of Medical Epidemiology, Biometrics and Informatics at University Medicine Halle.
The risk of post-COVID-19 condition is reduced after the fourth vaccination and the risk is also reduced in case of recurrent infection if post-COVID-19 condition has not occurred after the first infection
“We also found differences in the case of repeated coronavirus infections. People who did not develop post-COVID-19 conditions after infection and were re-infected had a lower risk of developing post-COVID-19 conditions than those who were infected for the first time,” says Professor Mikolajczyk.
The analysis also shows that the fourth vaccination reduced the risk of post-COVID-19 status. In phases where previous virus variants dominated, the number of vaccinations did not have a direct impact on the development of post-COVID-19 status, when comparisons were made within the respective virus variants.
“Even if this means that previous vaccination did not directly protect against post-COVID-19 conditions, indirect protection can be assumed. This is because according to currently available data, vaccinated people were less likely to develop symptomatic coronavirus infections or to suffer from severe infections, which in turn was associated with a higher risk of post-COVID-19 conditions,” says Prof. Mikolajczyk.
The researchers also found changes in the post-vaccination phase depending on the time interval between vaccination and infection. If the coronavirus infection occurred within three months of vaccination, participants were more likely to report a post-Covid-19 condition compared to those who had the infection at a longer interval from vaccination.
Further studies are needed to further explore this effect, particularly studies that examine the immune status prior to infection.
“Although the cause of post-COVID-19 symptoms is still not fully understood, the future outlook for people who have not yet developed post-COVID-19 symptoms is positive, as the risk due to Omicron infection has decreased and the risk has decreased substantially for people who already had a SARS-CoV-2 infection but did not subsequently develop post-COVID-19 symptoms,” said Dr. André Karch, professor at the University of Münster and last author of the study.
“Our results are consistent with the fact that the incidence of post-COVID-19 conditions, as observed last winter, is decreasing substantially. The detailed information from the German National Cohort before and after the pandemic, as well as ongoing research in the cohort, form a valuable basis for future studies on remaining research questions related to COVID-19,” says Prof. Karch.
more information:
Rafał Mikolajczyk et al, Possibility of post-COVID status in people with hybrid immunity; Data from the German National Cohort (NAKO), Journal of Infection (2024). doi: 10.1016/j.jinf.2024.106206
Provided by Universitätsmedizin Halle
Citation: Study on post-COVID-19 condition: Which factors impact risk (2024, July 4) retrieved July 4, 2024 from https://medicalxpress.com/news/2024-07-covid-condition-factors-impact.html
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