The New York State Department of Health and the Lewis County Public Health Department issued a joint statement expressing condolences over the child's death.

"We are deeply saddened by the death of a child in Lewis County associated with the ongoing measles outbreak. We extend our heartfelt condolences to the child's family and loved ones and ask that their privacy be respected during this difficult time," the statement said.

The health departments warned that measles is a highly contagious disease that can cause serious complications and even death, stressing that vaccination remains the best protection.

The New York State Department of Health said it had offered resources to Lewis County to assist with community outreach and local vaccination efforts, both in response to the case and as part of its broader efforts to support counties affected by the outbreak.

"We urge New Yorkers to ensure they are up to date on measles, mumps and rubella (MMR) vaccinations and speak to their healthcare provider about immunizations," the statement added.

The death comes four weeks after Governor Kathy Hochul declared a State Disaster Emergency in response to the measles outbreak affecting parts of New York and neighbouring states. The move expanded the pool of eligible healthcare professionals authorised to administer measles vaccines and enabled faster access to additional resources.

The department is working with county health authorities and local partners to provide MMR vaccines to unvaccinated individuals who request them. Officials are also monitoring and investigating reported cases, including through contact tracing, to prevent further transmission.

Residents contacted as part of these public health investigations have been urged to cooperate and share relevant information to help contain the outbreak.

As of October 24, New York had recorded 178 measles cases this year, including 170 outside New York City and eight within the city.

Reacting to the child's death, Governor Hochul expressed grief and extended her condolences to the bereaved family.

"I am heartbroken to learn that a child in Lewis County has died after contracting measles. As a mother and grandmother, I cannot imagine what this family is going through. My heart goes out to everyone who knew and loved this child," she said in a statement.

"Measles is highly contagious, and vaccination remains our best protection against this dangerous disease. This is New York's first measles-related death in 30 years, a devastating reminder of what's at stake when Washington deliberately erodes decades of progress in protecting Americans from preventable illnesses," she added.

What is measles?

Measles is a highly contagious viral respiratory disease that typically causes fever and a skin rash. It spreads through the air when an infected person coughs or sneezes. People can contract the virus by breathing in contaminated air or, less commonly, by touching an infected surface and then touching their eyes, nose or mouth.

The disease can cause serious complications, including pneumonia, hospitalisation, miscarriage, premature birth, brain swelling and death. It can also weaken the immune system's ability to fight other infections.

A rare but serious long-term complication is subacute sclerosing panencephalitis (SSPE), a progressive brain disorder that can develop years after an initial measles infection and cause permanent brain damage.