By Nicoletta Lanese

Declines in measles vaccination during the COVID-19 pandemic have been tied to an uptick in measles cases, deaths and major outbreaks worldwide.

Measles cases, deaths and outbreaks jumped dramatically between 2021 and 2022, a new report from the World Health Organization (WHO) and the U.S. Centers for Disease Control and Prevention (CDC) shows.

The research, published Friday (Nov. 17) by the CDC, revealed an 18% rise in the estimated number of measles cases between 2021 and 2022. That's an increase from about 7.8 million cases to 9.2 million. Measles deaths increased by 43% globally, from 95,000 in 2021 to 136,200 in 2022. The number of countries reporting "large or disruptive outbreaks" of measles jumped from 22 in 2021 to 37 in 2022, marking a 68% increase.

"The increase in measles outbreaks and deaths is staggering, but unfortunately, not unexpected given the declining vaccination rates we've seen in the past few years," John Vertefeuille, director of the CDC's Global Immunization Division, said in a statement.

"Measles cases anywhere pose a risk to all countries and communities where people are under-vaccinated," he said. "Urgent, targeted efforts are critical to prevent measles disease and deaths."

The WHO and UNICEF track the number of measles, mumps and rubella (MMR) vaccine doses administered worldwide each year and divide that number by the total population of children in the age group recommended to get the shot. Between 2000 and 2019, vaccine coverage with the first MMR dose rose from 72% to 86% worldwide. (One dose of the MMR vaccine is 93% protective against measles, while two doses are 97% protective.)

But in 2020, as the COVID-19 pandemic hit, coverage fell to 83%, and in 2021, it dropped to 81%, according to the CDC. Global coverage increased to 83% in 2022 as some countries rebounded from pandemic setbacks, but in low-income countries, vaccination rates continued to fall.

From 2019 to 2021, "coverage in low-income countries fell from 71% to 67%, then to 66% in 2022," the CDC states. Of 22 million children who missed their first MMR vaccine dose in 2022, more than half live in 10 countries: Angola, Brazil, the Democratic Republic of the Congo, Ethiopia, India, Indonesia, Madagascar, Nigeria, Pakistan and the Philippines.

"The lack of recovery in measles vaccine coverage in low-income countries following the pandemic is an alarm bell for action," Dr. Kate O'Brien, the WHO's director for immunization, vaccine and biologicals, said in the statement. "Children everywhere have the right to be protected by the lifesaving measles vaccine, no matter where they live."

Worldwide, coverage with the second MMR dose was 74% in 2022. Coverage with both the first and second doses needs to hit 95% to protect communities from outbreaks, according to the CDC.