Varicella-zoster virus vaccination under the exogenous boosting hypothesis: two ethical perspectives.

The varicella-zoster virus (VZV) causes two diseases: varicella ('chickenpox') and herpes zoster ('shingles'). VZV vaccination of children reduces exposure to chickenpox in the population and it has been hypothesized that this could increase the prevalence of shingles. This 'exogenous boosting' effect of VZV raises an important equity concern: introducing a vaccination program could advance the health of one population group (children) at the expense of another (adults and elderly). We discuss the program's justifiability from two ethical perspectives, classic utilitarianism and contractualism. Whereas the former framework might offer a foundation for the case against introducing this vaccination, the latter offers a basis to justify it.