Researchers around the world are pushing ahead with a raft of new options for a flu vaccine.

None will arrive in time to help sufferers this winter, but the most advanced—developed by Roche and Shionogi & Co.—could be on the market in Japan within months and available in the U.S. and Europe next winter. The flu kills as many as 650,000 people worldwide in its seasonal form and could wipe out millions of lives in a severe pandemic. The global influenza therapeutics market will swell to $1.2 billion by 2025, from $600 million in 2016, Acute Market Reports predicted in December.