Dr Paul Dugdale, author of the article, comments:
There is a health benefit of infection with one subtype of influenza because, like vaccination with that subtype, it will produce immunity to that subtype and can produce partial immunity to other subtypes. However, compared to vaccination, any possible increased efficacy of wild infection in preventing future infection would be more than offset by the health cost of actually having the bout of influenza. Therefore choosing not to be vaccinated on the grounds of possible net future benefit is not reasonable.
It may of course be quite reasonable for a healthy adult to decline vaccination on the grounds that it is not worth their while to reduce their chance of getting wild influenza. A discussion of their particular life circumstances will assist such a decision.