Vaccines do the precise opposite of what you just wrote - they expose you to huge numbers of viral particles ramping up your immune system so a state of enhanced immunity performance.
When you travel to foreign countries, you tend to take a number of vaccines just so that your body is ready to fight off the endemic diseases that are prevalent in the region you are traveling to.
I believe your parent was arguing that vaccines facilitate travel and that globalisation is anathema to monoculture. So vaccines indirectly attack the monoculture which you both think is a risk to our civilisation.
I wasn't - but I really like the point you are making. It had never occurred to me that the globalization of of travel is the antitheses of monoculture disease pools - But it's true - the Flu in China last year, quickly becomes a worldwide phenomenon six-nine months later.
That wasn't really my point so much as an attempt to clarify. In all likelihood globalisation at best buys time against the monoculture issue. If and when that hits, with globalisation, it will be commensurately larger than it would have been otherwise.
When you travel to foreign countries, you tend to take a number of vaccines just so that your body is ready to fight off the endemic diseases that are prevalent in the region you are traveling to.