Persons who were born before 1957 had a reduced risk of infection …  Persons who were born between 1957 and 1975 were at intermediate risk for infection. 1

In Ontario, people over 53 years old had about 1/6 the chance2 of getting the new H1N1; the those between about 33 and 53 had a little more than half the chance (odds ratios of about .15 and .42, respectively).

  1. David N. Fisman, Rachel Savage, Jonathan Gubbay, Camille Achonu, Holy Akwar, David J. Farrell, Natasha S. Crowcroft, & Phil Jackson (2009). Older Age and a Reduced Likelihood of 2009 H1N1 Virus Infection The New England Journal of Medicine, 361, 2000-20001[]
  2. I realize that odds ratios don’t quite say this, but it’s close enough[]