After recovering from COVID-19 infection, some patients suffer from persistent symptoms that can significantly impact their lives. But how many people are actually affected by this phenomenon? Reported figures vary considerably: British data from 2022 suggested 4 percent of those infected, while American studies calculated values of more than 10 percent. US researchers have now identified methodological shortcomings in some studies and criticized possible overestimation of the frequency of long Covid.
Scientists led by Vinay Prasad have criticized the methodological shortcomings and missing control groups in several studies in the journal “BMJ Evidence-Based Medicine.” This means it is unclear whether long-term symptoms are actually caused by COVID-19.
A December 2022 meta-study is particularly problematic, finding only 22 of 194 studies on Long Covid with control groups. The results show only small differences in symptom frequency.
Early in the pandemic, there was bias in case selection, with mild cases being overlooked. Additionally, there is an inconsistent definition of Long COVID, for example by the CDC (Centers for Disease Control). And prevention) In the United States.
The authors call for more in-depth research. German researchers such as Andreas Stollmach of Jena agree. They estimate that about 5-6% of those infected may be affected. These projections are based on 2020-2021 data and do not take into account the most recent Omicron variants, which appear to have less long-term impact.