The action makes measles one of the diseases for which federal health authorities have the authority to issue quarantine orders requiring people who have been diagnosed with measles or exposed to it to self-isolate to protect public health, a White House official said in a statement.

“This action was taken at the request of public health officials, who cited the cases of measles among Afghans who recently arrived in the US as well as several previous outbreaks of measles in recent years,” the official added, speaking on condition of anonymity.

The statement did not give details on the nature or length of the quarantine.

Measles was declared eliminated in the US in 2000, according to the US Centers for Disease Control and Prevention (CDC), meaning it was no longer constantly present. Thirteen cases of measles were confirmed in the US in 2020.

Flights carrying Afghan refugees to the US were temporarily paused because of four cases of measles, the White House said last week.

“All arriving Afghans are required to get vaccinated for measles, as well as for diseases like polio and Covid-19, as a condition of remaining in the US,” the official said.

Afghans are being vaccinated at military bases overseas before they fly to the US.

Afghans who were diagnosed with measles after arriving in the US “have been housed separately in accordance with public health guidelines”, and CDC has been conducting contact tracing, the official said.

Measles can be dangerous, especially for babies and young children, and pneumonia is among the possible complications, according to the CDC.