Fig. 1

Rates of hospital admission due to bronchiolitis. The y-axis shows the proportion of hospital admissions due to bronchiolitis compared to hospital admissions due to all causes during the first year of life

Z-test was carried out to test the null hypothesis that the proportion of cases in several groups are the same, followed by pairwise Z-test as post-hoc significance testing between pairs with p-values adjusted using the Bonferroni method. *p < 0.01, (∆)2020 vs. all other years, (§) 2020 vs. 2018 and 2019, (†) 2021 vs. 2018 and 2019, (‡) 2021 vs. 2018