U.S. Measles Cases Triple Last Year’s Total by July

Measles Cases This Year Triple Last Year’s Total, With Five Months Still Remaining The number of measles cases reported this year has more than tripled compared to the total from last year, with five months still left in the year. Data released Friday by the Centers for Disease Control and Prevention (CDC) shows 188 cases have been recorded across 26 states and Washington, D.C. While no deaths have been reported, 93 people, mostly children under 5, have been hospitalized.

This year, the U.S. has seen 13 measles outbreaks, the largest of which started at a migrant shelter in Chicago in March, leading to more than 60 cases. Recent cases have been reported in Massachusetts, Michigan, Minnesota, New Hampshire, New York, Oregon, and Vermont, with Massachusetts seeing its first case since early 2020.

In contrast, last year saw only four measles outbreaks and 58 cases in total. This year’s case count is the highest since 2019, when the U.S. nearly lost its measles elimination status due to over 1,200 cases, primarily in Orthodox Jewish communities in New York.

“Having this year be even worse than 2019 — there’s definitely potential for that,” said Dr. David Hamer, a professor of global health and medicine at Boston University. However, CDC models suggest that this scenario is unlikely.

Experts attribute the increase in cases to declining vaccination rates in the U.S. and a rise in global measles cases. The CDC reports that around 85% of those infected this year were either unvaccinated or had an unknown vaccination status. Many cases were linked to international travel, bringing the disease into the U.S. from other countries.

“We live in a global community where vaccination rates everywhere affect diseases that are transmitted in the United States,” said Dr. Erica Prochaska, a pediatric infectious diseases specialist at Johns Hopkins Children’s Center. “But the main issue is that in the United States, our population isn’t at the threshold of vaccination that we should be.”

A person infected with measles can spread the disease to up to 90% of people close to them if they are not immune. Public health officials recommend at least 95% vaccination coverage to prevent sustained transmission. As of the 2022-23 school year, 93% of U.S. kindergartners had received two doses of the measles, mumps, and rubella (MMR) vaccine, down from 95% in the 2019-20 school year. Twelve states and Washington, D.C., had rates below 90%.

“To me, what’s surprising is that the outbreaks aren’t more extensive,” said Dr. Gregory Poland, founder and director of the Mayo Clinic’s Vaccine Research Group. He added that some immunocompromised individuals cannot receive the MMR vaccine, so they rely on others getting vaccinated.

The U.S. effectively eliminated measles in 2000, meaning the disease is no longer constantly present, though occasional outbreaks still occur, originating from other countries. Before the first measles vaccine became available in 1963, around 3 million to 4 million people in the U.S. were infected annually, with 400 to 500 deaths each year.

“It’s sort of dropped out of people’s minds as an important issue,” Hamer said. Vaccine hesitancy, accelerated by misinformation during the pandemic, has contributed to the problem.

Globally, vaccination coverage for measles fell during the pandemic to the lowest levels since 2008. Hamer noted that lockdowns disrupted vaccination services in many low- and middle-income countries, and ongoing civil wars hindered efforts in countries like Ethiopia and Yemen, which now represent a disproportionate share of global measles cases.

From 2021 to 2022, measles cases increased by 18% and measles deaths by 43% worldwide, according to a joint report from the CDC and the World Health Organization. The number of countries experiencing large outbreaks rose from 22 to 37 during that time.

Common symptoms of measles include high fever, cough, conjunctivitis (pink eye), runny nose, white spots in the mouth, and a rash that spreads from head to toe. Around 1 to 3 out of every 1,000 children infected with measles die from complications such as pneumonia or brain swelling.