Is the show just poking fun at the science behind vaccines, do the creators really not know the science behind them either?
The city is going to be hit with a bio-engineered attack that will kill a decent percentage of those infected if not all those in the range.
But a vaccine taken will provide you immunity. Except for the fact that they stole the vaccine days before the attack. The body obvoiusly can’t build an immunity in days, that’s the point of them in the first place, so that the time it takes (weeks/months) to create the immune response cycle is taken before infection begins.
So, the show is either making fun of the population for blindly following ineffective vaccines, or the show is indicating that those who defend them don’t even know the science behind them.