“Today’s flu vaccines cannot prevent a devastating 1918-style pandemic. New advances are fueling a push for a long-lasting, broadly protective vaccine. Influenza kills hundreds of thousands of people each year.  Influenza is tough to stop because both major types of influenza virus — type A and type B — encompass a vast number of distinct strains, and immunity to one strain often does not confer protection from another. Researchers make educated guesses as to which strains are likely to spread in a given year, then develop a vaccine meant to stop them.”

nature.com