Urinary tract infections decreased in Finnish children during the COVID-19 pandemic

Social restrictions reduced the rates of respiratory infections in 2020, but studies on the rates of urinary tract infections (UTIs) during lockdown have had conflicting results. This study aimed to report UTI incidence during the first and second waves of COVID-19 pandemic in Finland. We conducted a retrospective register-based cohort study. The whole Finnish pediatric population (children under the age of 15 years, N = 860,000) was included. The yearly and monthly incidences of UTIs per 100,000 children in 2020 were compared to that of three previous years (2017–2019) by incidence rate ratios (IRRs) with 95% confidence intervals (CIs). A total of 10,757 cystitis and 4873 pyelonephritis cases were included. The yearly incidence of cystitis was 12% lower (IRR 0.88, CI 0.83–0.94) among children aged 1–6 in 2020 and 11% (IRR 0.89, CI 0.83–0.95) lower among children aged 7–14 in 2020 compared with previous years. The yearly incidence of pyelonephritis was 16% lower (IRR 0.84, CI 0.76–0.94) among children aged 1–6. No significant decrease were observed among children aged < 1 and 7–14. Conclusion: The incidence of cystitis and pyelonephritis during a period of social restrictions was lower than during 2017–2019, especially in children aged 1–6 years. These results raise the possibility of reducing the occurrence of urinary tract infections in children by improving hygiene measures. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00431-022-04389-9.