I actually agree with you but the CDC changed their definition of the word "vaccine" several times, most recently in 2021. The latest revision is now more scientifically accurate. But it's understandable how the changes caused confusion among some members of the public.

https://apnews.com/article/fact-checking-976069264061

It is not understandable without people acting in bad faith. Nobody with any sense would be closely monitoring that page's definitions because they are meaningless for policy. The only people who would care are conspiracy theorists and those who profit from them.

Besides calling me stupid and gullible, do you have an answer for my original point, which is that the Covid vaccines behave so differently than other vaccines, and that there may be a public health benefit in acknowledging that?

I get vaccinated against measles, or polio, or tetanus, and I don't have to worry about catching or spreading any of those diseases for years. With the Covid vaccine, some sources[0] say fully-vaccinated people are only half as likely as unvaccinated people to catch it (though obviously with less severe effects), and maybe about as likely to transmit it to others[1], and the protective effects wear off in a matter of months. That clearly doesn't line up with the public's traditional understanding of vaccines.

[0]: https://doh.wa.gov/sites/default/files/2022-02/421-010-Cases...

[1]: https://www.thelancet.com/journals/laninf/article/PIIS1473-3...

I didn't call you stupid, and everybody is at least a little gullible for stories that match their existing beliefs.

Do you get vaccinated for flu, the most administered vaccine in the US each year before the COVID vaccines became available? They are less effective than the mRNA COVID vaccines at preventing symptomatic disease and far less effective than the mRNA COVID vaccines at preventing severe disease.

The effectiveness of both is publicly acknowledged by the government. It just has nothing to do with the definition of "vaccine."

Other HN readers should consider this: had the social media companies not tried to limit the spread of misinformation, how many more conspiracy theories would you be parroting?