Same principle applies every year. They research the strains circulating in S Hemisphere, develop suitable vaccine (4 strains this year, instead of the more usual 3) and go into production in time for N hemisphere autumn. A mutation could make less virulent or serious and the vaccine might still offer some protection if it has mutated. If this process did not work to reduce the incidence of winter flu there would not be such a big effort put into it.
COUNTRY, CITY, AREA, PLACE -Game 21
Last weekend, in Rutland, the first statue in Britain of the late Elizabeth II was unveiled.