Before the Covid pandemic hit in 2020, public health experts would often say that vaccines had been victims of their own success.

People had simply forgotten how polio and measles could wreak havoc on Americans’ daily lives. If these diseases started surging again, experts said, parents would be scared straight.

This year, that prediction proved wrong.

Few minds were changed, even after the largest measles outbreak in the United States since 2000 hopscotched through unvaccinated communities, infecting hundreds and killing two young girls in Texas.

Texas was not a random epicenter for such an outbreak.

The percentage of kindergartners who have had measles shots in the state has fallen to 93.2 percent in the 2024-2025 school year from 96.9 percent in 2019 — slipping below the 95 percent threshold that guarantees broad immunity.

With loosened childhood vaccination laws, the portion of kindergartners without all their recommended immunizations has nearly doubled over the past five school years. About 25,000 kindergartners, more than in any other state, didn’t have at least one of their measles shots in early 2025, when the virus began to spread through the state.

In interviews with parents across Texas who oppose vaccinating their children, virtually all were resolute in their views. For them, opposition to vaccination is often a top priority, with some families even moving to the state for its more lax policies.