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

Health authorities work to notify people who were exposed to person who traveled through at least six counties

California public health officials are warning of a possible measles exposure spanning multiple counties after an infected and unvaccinated passenger traveled through the state via Amtrak trains and thruway buses.

The warning comes as the US faces its largest measles resurgence in more than three decades, fueled largely by growing vaccine hesitancy.