A new analysis published yesterday in the International Journal of Infectious Diseases finds the global measles incidence has declined over the past 30 years. But in 2021, measles caused 4.1 million cases, 48,100 deaths, and 4.2 million disability-adjusted life years (DALYs) among children under 5 years old, highlighting the significant threat the disease still poses to children in mostly low-income countries.
The study used data on measles incidence, mortality, and DALYs in children under 5 using the 2021 GBD (Global Burden of Disease) study, and information on measles containing vaccine (MCV) coverage in 204 countries from the Global Health Data Exchange (GHDx).
Overall, the study paints a picture of steady global declines in measles activity since 1990, but suggests the 2020 COVID-19 pandemic, with its disruptions to childhood immunization schedules, may mark the beginning of the end of measles progress for some nations.
Declines of 5% annually for 30 years
From 1990 to 2019, the global incidence rate of measles in children decreased by 5.85% annually (95% confidence interval [CI], -6.56 to -5.13), from 8,611.06 cases per 100,000 in 1990 to 1,413.59 per 100,000 in 2019.
In 2021, Somalia estimated the highest measles incidence rate at 8,964.82 cases per 100,000 population, followed by Vanuatu and Mali. Somalia and Mali also had the highest mortality rates, at 311.81 and 127.07 deaths per 100,000 population, respectively. Similarly, Somalia and Mali had the highest DALY rates in 2021.
In 2021, the global coverage of the first dose of the measles-containing vaccine (MCV1) was 80% (95% CI, 78% to 81%), while the coverage of the second dose (MCV2) was 68% (95% CI, 67% to 70%). Among the 204 countries analyzed, MCV1 vaccination coverage declined in 75 countries in 2021, with the largest reductions observed in Montenegro (-42.02; 95% CI, -58.36 to -19.26), Djibouti (-21.81%,), and Vanuatu (-20.52%).
Vaccine rate dropped for dose 1 after pandemic
“Prior to the COVID-19 pandemic, the global MCV1 coverage exhibited a consistent upward trend, with an EAPC [estimated annual percentage change] of 0.87 (95% CI: 0.79 to 0.96),” the authors wrote. “However, following the onset of the COVID-19 pandemic, MCV1 coverage declined, with an EAPC of -2.08 (95% CI: -3.30 to -0.85). In contrast, MCV2 coverage demonstrated an overall increasing trend throughout the period.”
After the onset of pandemic, 10 countries, including Zambia, saw an increase in measles incidence. According to the World Health Organization, global measles cases in 2023 reached 10.34 million, a 20% increase compared with2022.
While the overall trend still showed incidence decreasing, the authors note this may be due to reduced surveillance in low-income countries in the wake of COVID-19.
These disruptions have exposed millions of children worldwide to an elevated risk of measles infection.
“As of 2023, the WHO reports that global measles vaccination rates have not yet reached pre-pandemic levels,” the authors concluded. “These disruptions have exposed millions of children worldwide to an elevated risk of measles infection.”
