…The Measles showed up and spread amongst the wrong people. Herd immunity isn’t a switch that magically turns on and off based on small changes in figures. Sometimes you just get unlucky. You could even be right that an increase in undocumented immigrants caused this outbreak, but it would have been less likely to happen in a location with a higher vaccination rate.
But then its not the vaccination rates that were the driver - It was a policy change of brining in illegals (taht is what they are based on our laws) that we have no clue how sick they are from their lands.