Measles incidence and measles vaccine coverage in WHO South East Asia Region, 2017-2021

Abstract

Abstract

Introduction

Measles is a highly contagious disease caused by the measles virus of the paramyxovirus family. Measles remains one of the leading causes of childhood morbidity and mortality worldwide, accounting for more than 140,000 deaths in 2018. There was global concern about the high risk of measles outbreaks occurring due to the disruption of immunisation services during the COVID-19 pandemic. This study aimed to describe the incidence and immunisation coverage of measles in South East Asia Region (SEAR) between 2017 and 2021.

Methods

A cross-sectional descriptive study was undertaken using publicly available data from WHO, UNICEF, World Bank, and Our World in Data. Analysis included measles cases, estimated measles vaccine coverage, supplementary immunisation activities. Statistical analysis was conducted using STATA17.

Results

During the study period, a global measles peak was seen in 2019; regional peaks varied between 2018-2019. Global and regional measles incidence fell during 2020-2021. Globally, measles incidence was reported to be >80% lower in 2020 and 2021 than in 2019, with regions ranging from 61% to 91.5% lower. A large decline in incidence was seen in SEAR with a 67.3% drop in 2020 and 78.2% in 2021.

Globally, measles vaccine coverage fell during the study period. Global MCV1 coverage reduced by 3.5% in 2020 and 5.8% in 2021, but global MCV2 coverage rose by 1.4% in 2020 and remained unchanged in 2021. In 2020, the estimated national immunisation coverage (MCV1) declined in six SEAR countries ranging from 3% in Sri Lanka to 13.6% in Indonesia, while MCV2 coverage dropped in five SEAR countries ranging from 2.5% to 15.5%. There was a statistically significant negative correlation between country's population and elimination status (p<0.006). The association between incidence and MCV1 coverage was not significant.

Discussion

Although a drop in cases was detected in SEAR, India and Indonesia were included in top 10 countries globally with multiple reported measles outbreaks during June-November 2022. During a global pandemic, we would expect disruption to health systems including surveillance and access to routine health services, therefore the findings reported in this study could be under reporting and may not reflect the real situation.

Conclusion

This study found a decrease in measles incidence as well as reduced measles immunisation coverage in SEAR countries. This appears contradictory as low measles immunisation coverage may increase disease transmission causing large measles outbreaks in some SEAR countries. The findings are likely impacted by COVID-19 pandemic disruptions to measles surveillance and immunisation. The true situation may be clearer to see in the coming years as we emerge from the pandemic and reinstate health and data systems in countries. All countries need to focus on building stronger health systems and restoring immunisation and surveillance system for measles to allow progress to elimination to continue.