Peer-reviewed article
Time series analysis of routine immunisation coverage during the COVID-19 pandemic in 2021 shows continued global decline and increases in Zero Dose children
Beth Evans, Olivia Keiser, Laurent Kaiser, Thibaut Jombart ·
Summary
Written by AI, not yet AICS's view · claude-sonnet-5-5This study used WHO and UNICEF national coverage estimates for over 160 countries to compare routine childhood immunisation in 2021 with what pre-pandemic trends (2000-2019) would predict. It found that coverage kept falling in 2021 rather than recovering. Global DTP3 coverage was 86.5% against an expected 90.1%, which the authors say is a setback to 2005 levels. The number of children who received no vaccine doses (Zero Dose) also rose. The Americas, Africa and Asia were the most affected regions, and low- and middle-income countries were the most affected income groups.
Key points
- Global DTP3 coverage in 2021 was 86.5% against an expected 90.1%, a 3.6% decline (95% CI 2.6% to 4.6%) across 164 reporting countries.
- DTP1 coverage fell from an expected 93.7% to 90.9% (2.8% decline), and MCV1 coverage fell 3.8% compared with expected.
- About 3.4 million additional Zero Dose children were estimated on top of an expected 11.0 million (a 30.9% increase).
- Early signs of a rebound to pre-pandemic coverage were not seen in most countries.
- The Americas, Africa and Asia were the most affected regions, and low- and middle-income countries the most affected income groups.
Limitations
The analysis relies on modelled projections of expected coverage from 2000-2019 trends and on reported national estimates, so it cannot show the causes of the declines or what is happening within countries. The abstract does not say which individual countries were most affected.
Abstract
Abstract Whilst it is now widely recognised that routine immunisation (RI) was disrupted by the COVID-19 pandemic in 2020 compared to previous immunisation performance, the extent of continued interruptions in 2021 and/or rebounds to previous trends remains unclear, with sporadic surveys reporting signs of immunisation system recovery at the end of 2020. We modelled country-specific RI trends using validated estimates of national coverage from the World Health Organisation and United Nation Children’s Fund for over 160 countries, to project expected diphtheria, tetanus, and pertussis-containing vaccine first-dose (DTP1), third-dose (DTP3) and measles-containing vaccine first-dose (MCV1) coverage for 2021 based on pre-pandemic trends (from 2000-2019). We estimated a 3·6% (95%CI: [2·6%; 4·6%]) decline in global DTP3 coverage in 2021 compared to 2000-2019 trends, from an expected 90·1% to a reported 86·5% across 164 reporting countries, and similar results for DTP1 (2·8% decline; 95%CI: [2·0%; 3·6%]), and for MCV1 (3·8% decline; 95%CI: [4·8%; 2·7%]). 86·5% global coverage in 2021 represents a further decrease from that reported in 2020 and 2019, and translates to a 16-year setback in RI coverage, i.e., 2005 levels. Hypothesised and early signals of rebounds to pre-pandemic coverage were not seen in most countries. The Americas, Africa, and Asia were the most impacted regions, with low- and middle-income countries the most affected income groups. The number of Zero Dose children also continued to increase in 2021. DTP1 coverage declined worldwide from an expected 93·7% to a reported 90·9% (2·8% decline; 95%CI: [2·0%; 3·6%]) which translates into an additional 3.4 million Zero Dose children on top of an expected 11.0 million (30.9% increase) at the global level. We hope this work will provide an objective baseline to inform future interventions and prioritisation aiming to facilitate rebounds in coverage to previous levels and catch-up of growing populations of under- and un-immunised children.