Falling below herd immunity

Vaccination rates are still relatively high, but they need to be for herd immunity. For ProPublica, Duaa Eldeib, and Patricia Callahan, with graphics by Lucas Waldron, highlight states that fell below the recommended threshold for measles over the past decade.

At least 36 states have witnessed a drop in rates for at least one key vaccine from the 2013-14 to the 2023-24 school years. And half of states have seen an across-the-board decline in all four vaccination rates. Wisconsin, Utah and Alaska have experienced some of the most precipitous drops during that time, with declines of more than 10 percentage points in some cases.

“There is a direct correlation between vaccination rates and vaccine-preventable disease outbreak rates,” said a spokesperson for the Utah Department of Health and Human Services. “Decreases in vaccination rates will likely lead to more outbreaks of vaccine-preventable diseases in Utah.”

A state grid map with difference charts show decreasing rates. There is a thin margin for error.