At least two doctors who are former Republican congressmen think so (boldface mine):

If current polling trends hold, Republicans could lose their majorities in both the House and Senate this November. Most pundits attribute this potential blue wave to voters’ frustration with gas prices and the broader cost of living. But another issue is quietly hurting GOP candidates: our party’s often mixed messaging on vaccines…

Voters have certainly noticed — and they’re blaming Republicans. According to a recent KFF poll, more than 60% of voters now disapprove of the Trump administration’s handling of vaccine policy. Only 28% of independents approve. Democrats now hold a 16-point advantage on the issue: Forty-one percent of voters trust them more to handle vaccine policy, compared with 25% who trust Republicans…

President Trump has been a strong voice for vaccines, affirming that childhood immunizations work and encouraging parents to vaccinate their children. But he has promoted vaccine misinformation in the past, and in August, he signed an executive order to slim down the childhood vaccine schedule, and at the signing, suggested a link between vaccines and autism that decades of research have ruled out.

Meanwhile, the Department of Health and Human Services has thrown a key vaccine advisory panel into turmoil, threatened government vaccination programs, and downplayed the danger of measles — all at a moment when Americans are looking to their government for clarity…

Our party’s own data warned us that backsliding on vaccines would hurt our prospects. In 2025, the Republican polling firm Fabrizio Ward published a memo finding broad bipartisan support for routine childhood vaccines and warning that undermining them would cost votes.

The numbers are stark. Seventy-four percent of Americans say ensuring broad availability of Food and Drug Administration-approved vaccines should be a priority. Nearly 70% say they would be more likely to vote for a congressional candidate who vows to preserve vaccine access over one who seeks to rescind it. And crucially, more than 50% of voters say they’d be less likely to support a candidate who doesn’t support vaccines, even if they align with that candidate on other issues.

In other words, silence on vaccines is becoming a dealbreaker for voters who would otherwise vote Republican.

For a very long time, Republicans have been able to spout stupid rhetoric in many areas and thereby build out a Coalition of the Stupid, but now that they’re actually turning that rhetoric into action, they are finally starting to suffer for it politically.

Couldn’t have happened to a nicer bunch of assholes.