I assume you're referring to old people when you say 'vulnerable populations', but the problem is that old people are not always the only ones that get affected

I assume you're referring to old people when you say 'vulnerable populations', but the problem is that old people are not always the only ones that get affected during flu pandemics. During the Spanish flu pandemic, for example, half the deaths were in people 20 to 40 years old. https://en.wikipedia.org/wiki/Spanish_flu#Patterns_of_fatality https://en.wikipedia.org/wiki/Spanish_flu#Patterns_of_fatali...