Estimating global and regional disruptions to routine childhood vaccine coverage during the COVID-19 pandemic in 2020: a modelling study

Abstract

Background The COVID-19 pandemic and efforts to reduce SARS-CoV-2 transmission substantially affected health services worldwide. To better understand the impact of the pandemic on childhood routine immunisation, we estimated disruptions in vaccine coverage associated with the pandemic in 2020, globally and by Global Burden of Disease (GBD) super-region.Methods For this analysis we used a two-step hierarchical random spline modelling approach to estimate global and regional disruptions to routine immunisation using administrative data and reports from electronic immunisation systems, with mobility data as a model input. Paired with estimates of vaccine coverage expected in the absence of COVID-19, which were derived from vaccine coverage models from GBD 2020, Release 1 (GBD 2020 R1), we estimated the number of children who missed routinely delivered doses of the third-dose diphtheria-tetanus-pertussis (DTP3) vaccine and first-dose measles-containing vaccine (MCV1) in 2020. FindingsGlobally, in 2020, estimated vaccine coverage was 76•7% (95% uncertainty interval 74•3-78•6) for DTP3 and 78•9% (74•8-81•9) for MCV1, representing relative reductions of 7•7% (6•0-10•1) for DTP3 and 7•9% (5•2-11•7) for MCV1, compared to expected doses delivered in the absence of the COVID-19 pandemic. From January to December, 2020, we estimated that 30•0 million (27•6-33•1) children missed doses of DTP3 and 27•2 million (23•4-32•5) children missed MCV1 doses. Compared to expected gaps in coverage for eligible children in 2020, these estimates represented an additional 8•5 million (6•5-11•6) children not routinely vaccinated with DTP3 and an additional 8•9 million (5•7-13•7) children not routinely vaccinated with MCV1 attributable to the COVID-19 pandemic. Globally, monthly disruptions were highest in April, 2020, across all GBD super-regions, with 4•6 million (4•0-5•4) children missing doses of DTP3 and 4•4 million (3•7-5•2) children missing doses of MCV1. Every GBD super-region saw reductions in vaccine coverage in March and April, with the most severe annual impacts in north Africa and the Middle East, south Asia, and LatinAmerica and the Caribbean. We estimated the lowest annual reductions in vaccine delivery in sub-Saharan Africa, where disruptions remained minimal throughout the year. For some super-regions, including southeast Asia, east Asia, and Oceania for both DTP3 and MCV1, the high-income super-region for DTP3, and south Asia for MCV1, estimates suggest that monthly doses were delivered at or above expected levels during the second half of 2020.Interpretation Routine immunisation services faced stark challenges in 2020, with the COVID-19 pandemic causing the most widespread and largest global disruption in recent history. Although the latest coverage trajectories point towards recovery in some regions, a combination of lagging catch-up immunisation services, continued SARS-CoV-2 transmission, and persistent gaps in vaccine coverage before the pandemic still left millions of children under-vaccinated or unvaccinated against p...

Impact of the SARS-CoV-2 pandemic on routine immunisation services: evidence of disruption and recovery from 170 countries and territories

“…2 Modelled estimates of disruptions to routine childhood immunisation coverage in 2020 because of the COVID-19 pandemic had suggested even higher numbers of more than 8 million children who missed out on their third dose of diphtheria–pertussis–tetanus-containing vaccine (DTP3) and first dose of measles-containing vaccine (MCV1). 3 Although knowledge of these immunity gaps is crucial for nations to plan on addressing the situation, an accurate assessment of global vaccine disruptions would provide a clearer picture. Although immunisation programmes were severely affected in 2020, the full impact of disruption and ensuing consequences are not yet fully known, given that reporting delays and completeness, and limited data on catch-up activities, have affected routine monitoring of coverage.…”

Change in Measles Vaccine Coverage and Estimated Impact on Measles Mortality in Low and Middle Income Countries, 2020: An Investigation into Secondary Public Health Effects of the COVID-19 Pandemic Using the Lives Saved Tool

“…In addition, survey data relies to a variable degree on caregiver recall of vaccine receipt which can be another source of uncertainty and bias for the estimates. Some subjective decisions need to be also made in the process of generating WUENIC estimates (Kowalski, 2012) At the same time that the 2020 WUENIC estimates were released, another group led by the Institute for Health Metrics and Evaluation (IHME) released modeled estimates of measles vaccine coverage based on administrative and mobility data and a measure of vaccine coverage disruption (Causey, 2021). This group estimated that MCV1 coverage had declined by 7.9% from 2019, much higher than the estimated 2% decrease apparent in the WUENIC estimates.…”

Effect of evidence updates on key determinants of measles vaccination impact: a DynaMICE modelling study in ten high-burden countries

“… a ‘COVID-19 scenario’ based on the 2020 WHO-UNICEF routine coverage estimates [ 17 ]. In 2021 and 2022, routine coverage in each country is assumed to return to its 2020 level in the ‘Non-COVID-19’ scenario [ 28 ]. The expansion for routine immunisation programme by 1% absolute coverage increase a year is delayed to 2023.…”