Immunity can be boosted through exposure (indeed, this is one of the reasons why we may be seeing higher rates of shingles in young people, or why we see occasi

Immunity can be boosted through exposure (indeed, this is one of the reasons why we may be seeing higher rates of shingles in young people, or why we see occasional outbreaks of pertussis in people who were vaccinated awhile back). But for that, you are, at most, looking for the occasional transient exposure - not the bombardment that one is getting right now.