Worldwide routine immunisation coverage regressed during the first year of the COVID-19 pandemic

•We modelled expected DTP1, DTP3, and MCV1 coverage in 2020 based on historical trends from publicly-available vaccination coverage data.•We report a 2·9% (95 %CI: [2·2%; 3·6%]) global decline in DTP3 coverage from an expected 89·2% to a reported 86·3%; and similar results for DTP1 and MCV1.•These declines translate to levels of coverage last observed in 2005, thus suggesting a potential 15-years setback in RI improvements.•These declines are less than previous modelling – compatible with the hypothesis that coverage fell more acutely in early 2020 and then rebounded. Whilst COVID-19 vaccination strategies continue to receive considerable emphasis worldwide, the extent to which routine immunisation (RI) has been impacted during the first year of the pandemic remains unclear. Understanding the existence, extent, and variations in RI disruptions globally may help inform policy and resource prioritisation as the pandemic continues. We modelled historical, country-specific RI trends using publicly available vaccination coverage data for diphtheria, tetanus and pertussis-containing vaccine first-dose (DTP1) and third-dose (DTP3) from 2000 to 2019. We report a 2·9% (95 %CI: [2·2%; 3·6%]) global decline in DTP3 coverage from an expected 89·2% to a reported 86·3%; and a 2·2% decline in DTP1 coverage (95 %CI: [1·6%; 2·8%]). These declines translate to levels of coverage last observed in 2005, thus suggesting a potential 15-years setback in RI improvements. Further research is required to understand which factors – e.g., health seeking behaviours or non-pharmaceutical interventions – linked to the COVID-19 crisis impacted vaccination coverage.