State health officials say an infant in Orange County, California died of whooping cough, the state’s first pertussis death of 2019. The vaccination status of the infant or mother were not reported.

In 2016, only 52% of new mothers were vaccinated against pertussis, according to a report from the department.

The death comes amid warnings that California could be in for an outbreak in 2019. Whooping cough outbreaks tend to hit every three to five years, and California’s last were in 2010 and 2014.