History: The pandemic and growing hesitancy have slowed vaccination.
A false claim in the 1990s that combination meals, mumps and rubella vaccines caused autism led to a decline in vaccination rates. Public health campaigns then helped close much of this gap, but rates fell again during the Covid-19 pandemic, particularly in low-income countries.
The measles virus is particularly adept at finding pockets of vulnerability, but outbreaks of other vaccine-preventable diseases could follow, said Dr. Saad Omer, dean of the O’Donnell School of Public Health. UT Southwestern in Dallas.
“Measles is usually the canary in the coal mine,” Dr. Omer said.
In the United States this year, Philadelphia recorded nine cases of measles, Washington state confirmed three cases and was investigating three others, and several states were each tracing the contacts of a single case.
As of January, 49 countries were experiencing what the WHO calls “significant or disruptive outbreaks,” according to Dr. Natasha Crowcroft, senior advisor on meals and rubella at the organization.
Britain has confirmed 250 cases in 2023, most in children under 10. In Europe last year, one in five cases involved an adult aged 20 or older, according to the WHO.
These numbers may seem modest, but they indicate that public health officials should step up vaccination campaigns, Dr. Omer said.
“If a fire has just started, now is the time to pull out all the stops and put it out immediately, rather than waiting for it to spread,” he said.
The red line: Vaccination rates must not fall below 95 percent.
For the measures to remain under control, at least 95 percent of the population must be vaccinated. In Europe, the percentage of people who received a first dose fell from 96 percent in 2019 to 93 percent in 2022.
More than 1.8 million infants were not vaccinated between 2020 and 2022.
“We actually knew this was going to happen, so it’s not news to us,” Dr. Crowcroft said of the increase in single cases in Europe.
“There are times when there is absolutely no pleasure in being right, and this is one of them.”