The thing is the people who want to use vaccines as a delivery method for other things aren't just going to do it on the first batch of people and prove the conspiracy theorists right. So the real threat right now is not the real threat of intentional attack, but rather the high probability of unforeseen harm. Ultimately they will do everything they can to "prove" that the vaccines are safe and all the anti vax people are crazy. They will do this over a course of years, until they have made even the anti vax people think they are fools. Then they will start using the vaccines for delivery of whatever weapon they have planned.

So don't go "jesus on the street corner" with your warnings. It will only make it easier for everyone to write you off as stupid. Expect that this vaccine will become a regular thing like the flu vaccine. It will not be one and done. They will claim that the virus has mutated and you need another vaccine. They would use the flu vaccine but not enough people take it.