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The Food and Drug Administration approved a potentially revolutionary flu vaccine yesterday, and the push alerts came rolling in. The bureaucratic, multistep process for bringing new shots to market used to be the uncontroversial stuff of trade publications and medical journals, not national news. That has changed under an administration that tends to sow doubt about vaccines. But are Robert F. Kennedy Jr. and other Trump officials really backing down on their vaccine skepticism? Let’s weigh the evidence.

Hang on. Flu shots have been around forever. What makes this one special?

Call it a solution to the chicken-and-egg problem. For more than 70 years, most annual flu vaccines have come from a manufacturing process that incubates the virus in chicken eggs. That process takes about six months, which means scientists have to guess which strain will dominate the upcoming flu season and tailor the shot to it in advance. As a result, seasonal flu shots can be less protective against unforeseen strains. It’s a big issue: The flu kills tens of thousands of Americans each year. This new vaccine, which is called mFlusiva and comes from the pharmaceutical company Moderna, is the first seasonal flu shot that uses mRNA. That technology, which Moderna also uses in its COVID vaccines, lets scientists modify the shot much faster. Moderna’s clinical trial also showed that mFlusiva is more protective against the flu.

That all sounds good! What’s the catch? 

Moderna’s study found that........

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