The largest measles outbreak in Texas in more than 30 years showed no signs of slowing down on Friday, rising to 90 cases across seven counties. The increase represents a jump of more than 50% since the Department of State Health Services last released an update on Tuesday.

This is the tip of the iceberg,” said Rekha Lakshmanan, chief strategy officer for The Immunization Partnership in Houston, a nonprofit that advocates for vaccine access. “I think this is going to get a lot worse before it gets better.

An outbreak of measles is wreaking havoc in the South Plains region of Texas, where nearly 60 children have been confirmed to be infected. Physicians in the state say the current situation was