Respiratory infections in children and adolescents in Germany during the COVID-19 pandemic

Abstract

Background: Before the COVID-19 pandemic, acute respiratory infections (ARIs) in children were mainly characterised by three pathogens: respiratory syncytial viruses (RSV), influenza viruses and rhinoviruses. The impact of the COVID-19 pandemic and the measures taken in Germany (especially until the end of 2021) on the incidence of ARI in children and adolescents aged 0 to 14 years and the pathogens causing them has not yet been comprehensively analysed.

Methods: The evaluation is based on data from population-based, virological and hospital-based surveillance instruments up to the end of 2022.

Results: After the onset of the COVID-19 pandemic in early 2020, ARI rates remained almost consistently below prepandemic levels until autumn 2021, with only rhinoviruses continuously continuing to cause ARI. Only when the Omicron variant became predominant in 2022, there were measurable COVID-19 rates at population level in children, although COVID-19 hospitalisation rates remained comparatively low. RSV and influenza waves were initially absent and then occurred 'out of season', but were more severe than usual.

Conclusions: While the measures taken were effective in inhibiting the number of respiratory infections for almost 1.5 years, moderately frequent but rather mild COVID-19 cases occurred when measures were lifted. When Omicron emerged in 2022 COVID-19 became moderately frequent but led predominantly to mild illnesses. For RSV and influenza, the measures resulted in changes in their annual timing and intensity.

Keywords: COVID-19 PANDEMIC; GRIPPEWEB; INFLUENZA VIRUS; RESPIRATORY INFECTIONS; RHINOVIRUS; RSV; SARS-COV-2.

Figure 1

Rates of acute respiratory illnesses (ARI) and influenza-like illnesses (ILI) in children aged 0–14 years in 2020–2022^* Source: GrippeWeb

Figure 2

Rate of acute respiratory illness (ARI) and the respective proportions of the various pathogens attributable to the ARIs (areas) in children aged 0–14 years from 2020–2022^* Source: GrippeWeb and Virological Surveillance of the Working Group for Influenza (Arbeitsgemeinschaft Influenza)

Figure 3

Relative incidence of all ARI due to different respiratory pathogens in 0- to 4-year-olds compared to 5- to 14-year-olds (for the period of 2020−2022; proportion adjusted for ILI and non-ILI); the x-axis is plotted logarithmically Source: GrippeWeb and Virological Surveillance of the Working Group for Influenza (Arbeitsgemeinschaft Influenza)

Figure 4

Average number of acute respiratory illnesses (ARI) per person participating in GrippeWeb in the autumn/winter (CW 40 to CW 13) and spring/summer (CW 14 to CW 39) half-years from 2017–2022; age groups 0 to 4 years, 5 to 14 years and 15 years and older^* Source: GrippeWeb

Figure 5

Proportion of all infections in which two or more than two pathogens were detected; pooled for 2020–2022, stratified by age group Source: Virological Surveillance of the Working Group for Influenza (Arbeitsgemeinschaft Influenza)

Figure 6

Expected and observed proportion of co-infections by rhinoviruses and RS-viruses in 0- to 4-year-olds, from CW 36 to 52/2021 Source: Virological Surveillance of the Working Group for Influenza (Arbeitsgemeinschaft Influenza) and GrippeWeb

Figure 7

Expected and observed proportion of co-infections by influenza and RS-viruses in 0- to 4-year-olds, from CW 44 to 52/2022 Source: Virological Surveillance of the Working Group for Influenza (Arbeitsgemeinschaft Influenza) and GrippeWeb

Figure 8

COVID-19 rate in the population calculated from GrippeWeb participants with symptoms of ARI (COVID-ARI rate), stratified by children (0 to 14 years) and adults (15 years and older) from 2021–2022^*. Squares represent the cumulative (summed up) COVID-ARI rate of children at the end of 2021, mid-year 2022 and end of 2022 (right y-axis) Source: GrippeWeb and Virological Surveillance of the Working Group for Influenza (Arbeitsgemeinschaft Influenza)

Figure 9

Cumulative rate of severe acute respiratory infections (SARI) with COVID-19 in different phases of the 2020–2022 pandemic and in six different age groups. As the end of the Omicron-BA.5 phase had not yet been defined at the time of the study period of this paper, it was not yet possible to calculate cumulative rates for this phase Source: ICOSARI Hospital Sentinel

Figure 10

Cumulative rates of SARI with ICD-10-coded influenza diagnosis, RSV diagnosis or COVID-19 in 0- to 4-year-olds and 5- to 14-year-olds, shown for the strongest or only pathogen waves in the period under consideration (2020–2022). Waves were ordered chronologically as follows: Influenza early 2020, RSV 2021, COVID-19 (Omicron BA.1 and BA.2) early 2022, RSV year-end 2022 and influenza year-end 2022 Source: ICOSARI Hospital Sentinel