Alex Rider. He's a teenage spy in a set of books by the author Anthony Horowitz. I read those books as a kid. Can't remember which one, but in one of them the evil villain he was fighting and trying to stop did something scarily similar to this/what you were mentioning.

What the evil villain did was put tiny gold nanoshells containing poison in standard flu vaccines, waited until everyone got one, and then the plan was to use thz beams sent out by radar dishes on weather balloons/tall buildings to break the shells (likely through resonance), releasing a deadly poison to basically kill everyone.

What's scary is I just glanced at another one of the books, and in that one the evil person was developing a genetically modified strain of corn that could release a deadly virus (epicyte gene and sterilization, anyone).

These books were sold in my schools book fair back when I was in school, and I think one of them was turned into a Hollywood movie. I'd be very interested in knowing if there's anything sketchy about this Horowitz guy.