Researchers at the Universitätsmedizin Halle revealed that about 19 percent of people who contract a respiratory infection develop lingering symptoms lasting twelve weeks or longer. According to the DigiHero study published in Deutsches Ärzteblatt, this post-acute infection syndrome affects roughly one in five patients across different pathogens.
Recovering from a common respiratory bug does not always mean a return to full health.
DigiHero Study Tracks Post-Acute Infection Syndromes Across Germany
The investigation was conducted between September 2024 and August 2025 by a research team at the Universitätsmedizin Halle.
Among the survey respondents, 48 percent reported experiencing at least one respiratory infection during the tracked timeframe, with younger individuals logging infections more frequently. The extensive dataset offers a clear baseline for evaluating how frequently long-term complications arise in the general population after the acute phase of an illness fades.
Symptoms Mimic Long COVID Across Both Corona and Influenza
When symptoms linger for more than twelve weeks past the initial infection, medical professionals classify the condition as a post-acute infection syndrome, commonly known as PAIS. The analysis demonstrated that these lingering health troubles are not exclusive to a single pathogen.
Dabei treten solche Beschwerden nach Infektionen mit dem Coronavirus, Influenza und anderen Atemwegserregern in ähnlicher Häufigkeit und Ausprägung auf.
Patients infected with the coronavirus and those who contracted influenza experienced strikingly similar clinical profiles. The most prevalent complaints included profound fatigue, reduced physical stamina, shortness of breath, and a general lack of energy. Nearly 90 percent of affected respondents stated that these ongoing health hurdles moderately to severely disrupted their daily routines.
Prof. Dr. Rafael Mikolajczyk, Director of the Institute for Medical Epidemiology, Biometry and Informatics at Universitätsmedizin Halle and senior author of the current study, noted that ranging from severe exhaustion and low physical resilience to shortness of breath, there is a wide variety of symptoms that can occur with PAIS, and added that the complaints are often medically difficult to classify and correspondingly hard to treat.
Jonas Frost, first author of the study and research associate at Universitätsmedizin Halle, explained that previously there was a lack of data on how frequently PAIS occurs in the general population following the corona pandemic, which symptoms arise, and to what extent affected individuals utilize medical care.
Friederike Peter, co-first author of the study from Universitätsmedizin Halle, summarized the findings by stating that their analysis shows PAIS is a relatively frequent and clinically relevant phenomenon following respiratory infections and is not limited to a specific pathogen.
Age Factor and Patient Recovery Timelines
The likelihood of developing chronic post-viral symptoms climbs steadily as people age. While 13 percent of infected individuals aged 20 to 29 reported prolonged issues, that risk jumped to 21 percent among those aged 60 to 69. Accounting for survey variables and participant recall bias, the research team estimates the true risk of developing PAIS after an infection in this timeframe at roughly 16 percent.
Recovery proves slow for the vast majority. Von den Infizierten berichteten rund 4.300 Personen – etwa 19 Prozent – über Beschwerden, die zwölf Wochen oder länger anhielten. Within twelve months of onset, only about 17 percent of those suffering from long-term symptoms had fully recovered, meaning the remainder dealt with health challenges stretching past a full year.
Healthcare Utilization and Remaining Knowledge Gaps
Faced with persistent health struggles, 58 percent of symptomatic individuals sought medical assistance. Of those who visited a doctor, 82 percent received some form of medical treatment, leaving a notable fraction without specific clinical interventions despite entering the healthcare system.
Despite clear epidemiological tracking, the underlying biological mechanisms driving PAIS remain poorly understood.