Country is in the middle of worst measles outbreak since 1991, with more than 5,400 cases nationally

The United States could lose its measles elimination status this week, an event likely to cement health secretary Robert F. Kennedy Jr’s legacy of meddling in vaccine policies amid the worst outbreak of the virus in the US in 35 years.

If the US loses its measles-free status, it would join Canada and several European and Asian nations that had eliminated the disease only for it to return.

“That is a tremendous step backwards,” said Dr Paul Offit, director of the Vaccine Education Center, an attending physician in the division of infectious diseases at Children’s Hospital of Philadelphia, and a prominent critic of Kennedy.

A panel of eight independent experts will consider the epidemiological evidence in Washington DC, part of a group called the Pan American Health Organization (PAHO), a regional branch of the World Health Organization (WHO). The PAHO director will make the final call.