High rates of viral co-detection in outpatient children with acute respiratory infections after the easing of preventive measures against Covid-19 in Germany

Following the easing of preventive, non-pharmaceutical COVID-19 interventions (NPIs) during the late phase of the pandemic, acute respiratory infections (ARI) in children reemerged. We investigated the viral etiology, seasonality and clinical characteristics of children with ARI treated in primary care practices during this period. We conducted a prospective, observational study on children ≤ 14 years of age, presenting with acute upper (URTI) or lower (LRTI) ARI in five pediatric primary care practices in Wuerzburg, Germany, from 10/2021 to 05/2022. A maximum of eight children per practice were included on one predefined day per week. Oropharyngeal swabs were analyzed using (multiplex) PCR for 18 viral pathogens. A total of 521 children (median age 3.3 years; IQR 1.6–5.5; 52% male) with ARI were enrolled (28% LRTI). At least one virus was detected in 85%, with human rhinovirus (HRV) (30%), Respiratory Syncytial Virus (RSV) (22%), and SARS-CoV-2 (16%) being the most frequent viruses. Co-detection (≥ 2 viruses) occurred in 156 (30%) patients, were most frequent in children < 2 years of age (38% of 164), and their rate decreased with increasing age (p = 0.012). Bocavirus (88% of 56), adenovirus (80% of 48) and endemic coronaviruses (70% of 42) showed the highest proportion of co-detection. RSV and human metapneumovirus (hMPV) were predominant in LRTI, whereas HRV and SARS-CoV-2 were more prevalent in URTI. The LRTI rate was 32% of 288 mono-detections and 23% of 156 co-detection. During fall/winter 2021/2022, viral co-detection were common, possibly as a consequence of easing COVID-19-related NPIs, but were not associated with more severe clinical characteristics.