[Domenic_S]

Huh? The FDA's main guidance document on this topic, issued in 2007 with no major overhaul since [0], states that comparative efficacy or effectiveness data is valuable when:

- The comparator vaccine is indicated for the same population.

- The comparator has existing clinical effectiveness data.

In other words, the trial design should use a benchmark that makes sense given what doctors and guidelines actually recommend today. For older adults, evidence over the past 15+ years has shown that enhanced flu vaccines often provide better protection than standard-dose ones. The study used standard-dose vaccines as far as we can see.

The only oddity here is that the FDA apparently approved the study previously

[0] https://www.fda.gov/regulatory-information/search-fda-guidan...

[sephamorr]

The document describes proof of effectiveness as supported by demonstrating "non inferiority to... a US licensed product". So yes, a (licensed) benchmark, but I see no references to a requirement for only testing against the best standard of care. It's a separate question about whether it should be though, and the cfr is quite vague throughout, so I would probably expect this isn't an illegal move (assuming arbitrary and capricious isn't held by a court), but I don't see it supported by precedent.