The United States is in the middle of what’s shaping up to be the worst measles outbreak of this century.

The outbreak began within a small religious community in West Texas in January, but it has since spread across four states in the Southwest. Two school-aged children and one adult have died so far. The number of reported cases is set to surpass 1,000 this week — though the real count may be much higher.

The challenge measles presents in 2025 is very different than in the years before a vaccine was introduced in the 1960s. In those days, we had limited defenses against the virus, which was highly contagious and highly dangerous to young children.

Today, we have perhaps the single best defense we have against any virus: a vaccine that is 97 percent effective in preventing measles, far better than vaccines against diseases like the flu or Covid. We have the means to snuff out measles. We’re just not using it, thanks in large part to an anti-science backlash that has gotten fresh momentum with the rise of vaccine skeptic Robert F. Kennedy Jr. to lead the nation’s health agency.

Now we’re in a dangerous moment of backsliding on decades of progress. How did it happen? The following four charts tell the story of how the US is losing the fight against measles — and why:

The January outbreak is now the single largest since the United States managed to eradicate, or end the disease’s natural spread in the country, in 2000:........

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