Also, what's hard to remember is that we already had (or were very close) to a vaccine candidate for H1N1 by the time it was declared a pandemic in April 2009. Even before the U.S. declared a national state of emergency, more than 11M+ vaccine doses had been produced for the U.S alone: https://www.cdc.gov/h1n1flu/vaccination/updates/101609.htm

AFAIK, scientists are still trying to develop a covid-19 vaccine candidate. And after they have one, there will be many months before millions of doses can be produced and distributed.