Self-testing for five respiratory viruses in adults ≥50 years of age in Germany for longitudinal monitoring of community-acquired acute respiratory infections

OBJECTIVES: We aimed to systematically assess acute respiratory infection (ARI) episodes outside medical settings in older adults in Germany to capture real-time, community-based data on incidences, symptoms, healthcare use, and work absenteeism. METHODS: German adults aged ≥50 years enrolled in the VACCELERATE Volunteer Registry received multipathogen antigen test kits (MAK5) for self-testing, detecting SARS-CoV-2, influenza A and B viruses, respiratory syncytial virus (RSV), and adenovirus (AdV). From May 2024 to May 2025, participants self-tested upon ARI symptoms and reported test results, symptoms, episode duration, medical consultations, illness-related work absenteeism, pre-existing conditions, vaccination history, and previous infections. RESULTS: Of 3162 individuals enrolled, 2890 (91.4%) actively participated. Overall, 45.5% (1314 of 2890) reported no ARI, 31.4% (908 of 2890) 1, and 22.8% (658 of 2890) ≥2 episodes (median: 2; interquartile range [IQR]: 1-3; range: 0-6). Among 2569 tests, 752 (29.3%) were positive, including 53 (7.0%) codetections, yielding 833 pathogen detections. Cumulative incidence was 18.5% (524 of 2890) for SARS-CoV-2, 4.0% (114 of 2890) for AdV, 3.8% (110 of 2890) for influenza A virus, 1.8% (52 of 2890) for RSV, and 1.1% (33 of 2890) for influenza B virus. Median ARI duration ranged from 6 days (IQR: 5-8 days, range: 1-20 days) for SARS-CoV-2 to 9 days (IQR: 5-15 days, range: 1-26 days) for RSV. Median age ranged from 56 years (IQR: 54 -61 years; range: 50-80 years) for AdV to 61 years (IQR: 56-67 years; range: 51-81 years) for RSV. Medical consultation occurred in 28.8% (15 of 52) RSV, and 15.3% (80 of 524) SARS-CoV-2 cases. SARS-CoV-2 detections accounted for 31.1% (222 of 713) of illness-related work absences and 2 of 9 (22.2%) hospitalizations. CONCLUSIONS: This study enabled real-time, community-based monitoring of five endemic pathogens. Although SARS-CoV-2 accounted for highest cumulative incidence and overall disease burden, RSV detections, though less frequent, were predominantly observed in older adults and were associated with greater per-case burden, reflected in longer illness duration and increased healthcare utilization.