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

Abstract text: We modelled historical, country-specific routine immunisation 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 evaluate changes in coverage in 2020 by comparing model predictions to WUENIC-reported coverage. We report a 2.9% (95%CI: [2.2%; 3.6%]) global decline in DTP3 coverage, and important increases in missed immunisations in some countries with middle-income countries, and the Americas, being most affected. CC-BY-NC 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted December 5, 2021. ; https://doi.org/10.1101/2021.12. 03.21267195 doi: medRxiv preprint NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice. The COVID-19 pandemic has impacted society and public health infrastructures worldwide, influencing mobility [1], access to health services [2], livelihoods and poverty [3]. While COVID-19 vaccination strategies continue to receive considerable emphasis [4,5], the extent to which routine immunisation (RI) has been impacted during the first year of the pandemic remains unclear. Indeed, the World Health Organisation (WHO) pulse surveys reported disruptions in the first half of 2020 [2], and while some later studies suggested a potential recovery [6], recent observations again hinted at global coverage declines [7]. RI is estimated to prevent four to five million deaths worldwide every year [8]. As such, there is an urgent need for assessing potential changes in RI coverage, as declines may result in considerable added morbidity and mortality. A global decline in RI coverage We investigated changes in RI coverage using two key indicators: diphtheria-tetanuspertussis first-dose (DTP1) and third-dose (DTP3). DTP3 serves as a general marker for immunisation system performance, used by national and global immunisation stakeholders [9]. DTP1 is used as a proxy for inequity quantifying Zero Dose (ZD) children, those that receive no childhood vaccinations [10]. We compiled vaccination coverage data from the WHO and United Nations Children’s Fund (UNICEF) Estimates of National Immunisation Coverage (WUENIC) [11,12] for the last 20 years. We used AutoRegressive Integrated Moving Average (ARIMA) modelling [13] to capture temporal trends in coverage for each country from 2000 to 2019, and predicted expected coverage levels in 2020 (Figure 1). All analyses were conducted using R [14] and can be reproduced using a publicly available reportfactory [15] including all required data and scripts [16]. Insert: figure1_coverage. pdf Figure 1: Expected and reported 2020 vaccine coverage for DTP1 and DTP3: example of five countries with most additional missed DTP3 immunisations in 2020. These graphs show WUENICreported coverage data (black dots) and the corresponding ARIMA predictions and the associated 95% confidence intervals (red bars). After excluding countries for which reliable coverage predictions could not be obtained (see Supplementary Text for details), we were able to estimate differences between expected and observed coverage in 2020 for 167 countries for DTP3 (Figure 2) and DTP1. Unfortunately, the exact magnitude of coverage decline was often hard to assess for individual countries . CC-BY-NC 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted December 5, 2021. ; https://doi.org/10.1101/2021.12. 03.21267195 doi: medRxiv preprint