key: cord-0866260-68tdggts authors: Evans, B.; Jombart, T. title: Worldwide routine immunisation coverage regressed during the first year of the COVID-19 pandemic date: 2021-12-05 journal: nan DOI: 10.1101/2021.12.03.21267195 sha: 054b5bf8d010580c2ef67957adbe483c8f6bac32 doc_id: 866260 cord_uid: 68tdggts 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. 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. 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. While the global decline in DTP3 coverage is in itself an important result, it is also essential to characterise potential differences among affected countries. Whilst individual country is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted December 5, 2021. ; https://doi.org/10.1101/2021.12.03.21267195 doi: medRxiv preprint countries (HICs; mean change: -0.9%; 95% CI : [-2.2%; 0.3%]) did not show any significant change. As UN regions and income groups are highly correlated (non-parametric Chi-square test: X 2 = 115.4, p < 10 -5 ), we also tested whether heterogeneities due to one variable (regions or income groups) remained after accounting for the effect of the other one. Interestingly, regional differences remained after accounting for differences in income groups (ANOVA: F = 5.67, df = 159, p < 2.7x10 -4 ), but evidence for the converse was weak (ANOVA: F = 2.67, df = 159, p = 0.05). Insert: figure3_heterogeneity_dtp3.pdf Table 1 details results for the 10 countries with point estimate greatest additional missed DTP3 immunisations in 2020 (see also Figure 1 ). Similar trends are seen for ZD children using DTP1 results. Detailed results for all analysed countries can be found in the Supplementary Tables S1 (DTP1) and S2 (DTP3). . 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. The copyright holder for this preprint this version posted December 5, 2021. ; https://doi.org/10.1101/2021.12.03.21267195 doi: medRxiv preprint Numbers displayed in bold font indicate significant differences between expected and observed coverage. LIC: Low-income Country. LMIC: Lower-middle-income Country. UMIC: Upper-middle-income Country. The estimated changes in RI coverage reported in this study suggest a smaller global decline (approximately 1/3rd the magnitude) than previously found using alternative methodology and data [18] . We believe our findings may be more robust owing to a more comprehensive dataset including data from more countries (167 here vs. 94), plus increased data from the end of 2020 (annual here vs. majority of data from January-September 2020), and the use of WUENIC-reported data (less prone to data quality and completeness issues than administrative data). The observed discrepancies are compatible with a rebound of global RI coverage in late 2020 [6] . The RI disruption observed in this study suggests there may be greater risk of vaccinepreventable disease outbreaks in the coming years, in the absence of Supplementary Immunisation Activities (SIAs) to reach missed children. ZD populations in key ZD "hotspots" (e.g., India, Pakistan, and Indonesia) are estimated to have increased significantly in 2020, posing a genuine public health threat in the coming years. To alleviate such risks and reduce immunisation inequities, SIAs targeted specifically at these populations should be considered. Additional research is needed to investigate heterogeneities in RI decline at finer scales and identify subpopulations which may have experienced even greater losses to RI coverage. RI disruption may be worsened by the acceleration of COVID-19 vaccination campaigns, particularly in low-and middle-income countries where absorption capacity may be challenged [19, 20] , potentially competing with RI services. Careful monitoring of the interaction, trade-offs and synergies between RI and COVID-19 vaccinations is essential. Further studies are needed to understand which factors linked to the COVID-19 crisis . 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. The copyright holder for this preprint this version posted December 5, 2021. ; impacted vaccination coverage, such as changes in health-seeking behaviours or nonpharmaceutical intervention policies, in order to successfully and efficiently address pandemic-associated losses to coverage. As the COVID-19 pandemic continues to affect healthcare systems globally, maintaining the appropriate balance between access to routine immunization and pandemic response will be essential to reduce both the direct and indirect mortality and morbidity associated with COVID-19. This research provides a transparent and replicable rationale for estimating gaps in RI coverage across countries, producing an objective measure for missed immunisations and coverage disruptions. As such, it can form a basis for identifying countries most affected by declines in RI coverage and prioritising efforts to alleviate the indirect impact of COVID- Impact of COVID-19 pandemic on mobility in ten countries and associated perceived risk for all transport modes Pulse survey on continuity of essential health services during the COVID-19 pandemic: interim report Impact of COVID-19 on people's livelihoods, their health and our food systems n Board on Population Health and Public Health Practice, Board on Health Sciences Policy, Committee on Equitable Allocation of Vaccine for the Novel Coronavirus. Framework for Equitable Allocation of COVID-19 Vaccine International collaboration to ensure equitable access to vaccines for COVID-19: The ACT-accelerator and the COVAX facility Impact of the SARS-CoV-2 Pandemic on Routine Immunization Services: Evidence of Disruption and Recovery From 169 Countries and Territories World Health Organization. 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