How have respiratory tract infections changed in the post-covid era for children under 5 years?

Abstract Background Social distancing measures introduced in response to the covid-19 pandemic reduced transmission of all respiratory pathogens. Exposure to respiratory pathogens in early life affects future lung health. We aimed to describe changes in the incidence of respiratory tract infections (RTIs) in children <5 years in England in the post-pandemic era. Methods Population-based retrospective cohort study using electronic health records. We included all children aged <5 years registered with a primary care practice from April 2016 to March 2023. We compared monthly GP consultation rates for RTIs in the two post-pandemic years (April 2021 - March 2022 and April 2022 - March 2023) with corresponding months during pre-pandemic years (April 2016 - February 2020). Results There were 3 045 701 respiratory tract infections among 2 894 539 children <5 years registered with a GP practice during the study period. Pre-pandemic, monthly RTI rates varied from lows of 29.1 per 100 child-years in August to highs of 108.8 per 100 child-years in November. In 2021/22, monthly RTI rates were bimodal peaking in June and October, although the winter peak was lower than pre-pandemic years and mean monthly RTI rates were ∼15% lower overall. In 2022/23 mean monthly RTI rates remained ∼15% lower than pre-pandemic years, but there was a single peak in December 2022 of 117.6 RTIs per 100 child-years, exceeding the pre-pandemic winter peaks by 8.1%. Conclusions Overall, monthly RTIs in post-pandemic years were 15% lower than pre-pandemic years. However, there was a concerning peak in December 2022 that exceeded the winter peaks from previous years. Comparisons with national surveillance data suggest this peak reflects changes in RTI incidence, particularly among group A streptococcal infections, but this peak may also reflect changes in access to care or healthcare seeking behaviour. Continued monitoring of post-pandemic seasonal patterns will assist in planning for health service use. Key messages • Respiratory tract infections in children <5 years in post-pandemic years were 15% lower than pre-pandemic years, but winter peaks in incidence may be of greater magnitude in the post pandemic era. • Ongoing monitoring of patterns of respiratory tract infections in young children is important for future health service planning and delivery.