On two-dose measles vaccine efficacy

In a short explainer, the subject stated that two doses of the measles vaccine are about 97 percent effective at preventing measles. The claim drew a large and contested reply thread. It was accepted into Lane A under a matched pledge.

"Two doses of MMR are about 97% effective against measles. One dose is about 93%."

The figure is specific, falsifiable, and central to a public-health decision many viewers make. Materiality and reach were both clear.

What the record shows

The 97 percent figure for the two-dose schedule, and 93 percent for a single dose, are the standing estimates published by the CDC and supported by the peer-reviewed effectiveness literature the agency cites. These are automatically qualifying sources under the Evidence Standard.

The subject provided the CDC's vaccine effectiveness page and two of the underlying studies on request. The numbers were quoted as central estimates, not as guarantees — a distinction the original post preserved.

Finding

The claim was substantiated at the precision stated. The subject represented the range honestly, including the lower single-dose figure, and did not overstate certainty.

The record stands as presented.