The United States recorded 75 new cases of the measles in the last week, totaling 839 cases in the country’s worst outbreak of the virus since 1994, federal health officials said on Monday.
The Centers for Disease Control and Prevention reported a 9.8% increase in measles cases across 23 states since May 10, a resurgence that public health officials have attributed to the spread of misinformation about the measles vaccine.
A vocal fringe of U.S. parents oppose the measles-mumps-rubella vaccine, believing, contrary to scientific consensus, that it can cause autism. Federal health officials said this outbreak has mostly affected children who have not received the vaccine, which confers immunity to the disease.
The outbreak has not spread to any additional states since last week, when Pennsylvania became the latest state to confirm at least one case.
Although the virus was eliminated from the country in 2000, meaning it was no longer continually present year round, outbreaks still happen via travelers coming from countries where measles is still common, the CDC says.
This outbreak has escalated since 82 people in 2018 and more than 40 people in 2019 brought measles to the United States from other countries, most frequently Ukraine, Israel and the Philippines, federal officials said.