California warns of measles exposure across six counties from unvaccinated train passenger

California public health officials are warning of possible measles exposure spanning at least six counties after an infected, unvaccinated passenger travelled through the state on Amtrak trains and connecting thruway buses. Authorities are working to notify people who may have been exposed during the journeys. The warning comes as the US faces its largest measles resurgence in more than three decades, driven largely by growing vaccine hesitancy.