measles

Measles Deaths Increased 43% Worldwide in 2022

The increase in mortality follows steady declines in measles vaccination rates during the pandemic among children in low-income countries, according to a new CDC/WHO report coauthored by Allison Portnoy.

As one of the world’s most contagious respiratory diseases, measles can spread quickly in undervaccinated populations. After years of decline in measles vaccinations during the COVID-19 pandemic, measles cases rose by 18 percent and deaths increased by 43 percent worldwide compared to 2021 rates, according to a new report by the Centers for Disease Control and Prevent and World Health Organization. 

The Morbidity and Mortality Weekly Report was coauthored by Allison Portnoy, assistant professor of global health at the School of Public Health.

Global measles vaccine coverage increased slightly in 2022 from 2021, but it did not increase among low-income countries—particularly among children, the population that is most at risk of severe complications and death, the report found. Measles vaccination coverage remains below pre-pandemic levels and well below the minimum coverage needed to successfully eliminate the disease at a regional or global level.

The report urges countries and global organizations to accelerate vaccination efforts among children and expand surveillance programs to achieve measles elimination.  

“To avoid the return or further spread of measles in countries where it had previously been eliminated, it is critical that we work to increase measles vaccine uptake and improve primary healthcare to reduce measles fatalities,” says Portnoy, whose research focuses on vaccine decision science and policy, particularly around increasing vaccination rates in high-burden settings.

The report found that low-income countries, where the risk of death from measles is highest, continue to have the lowest vaccination rates at only 66 percent for the first of the two-dose series, compared to 67 percent in 2021 and 71 percent in 2019. To achieve and maintain measles elimination, experts say vaccination coverage needs to reach 95 percent of the two-dose series. 

The new report draws upon an estimation framework for measles case fatality ratios (CFRs) that Portnoy developed in 2019 in a study published in The Lancet Global Health. The framework was updated earlier this year in a study by Portnoy and Alyssa Sbarra of the London School of Hygiene & Tropical Medicine. The report utilizes the authors’ CFR estimates based on estimated measles incidence to gauge the global measles death rate in 2022. 

The measles vaccine remains one of the most effective vaccines—with two doses, it is 97 percent effective at preventing measles infection for life. But nearly 33 million children around the world are un- or undervaccinated against this disease, including 21.9 million infants who missed their first measles vaccine dose and an additional 11 million children who received only a first dose, the report states. More than half of the 22 million children who missed their first measles vaccine dose in 2022 live in 10 countries: Angola, Brazil, Democratic Republic of the Congo, Ethiopia, India, Indonesia, Madagascar, Nigeria, Pakistan, and Philippines. 

“Often, the children that do not receive vaccination live in places with less access to healthcare—and therefore the children who get sick are also more likely to die,” Portnoy says. “Improving vaccination programs to reach these children will require investments in primary health systems.”