Does the UV Germicidal Lamp for your A/C work? Is it worth it?

The past two months have been rough at my house. Everyone got sick, and the 6mo old baby got pneumonia. So, my Mother recommends the UV lamp to help kill bacteria in the A/C system since she thinks that would have helped keep the spread of germs down. My Wife's Great Grandmother has one of the UV systems in her A/C system too. Is this some sort of fad with the older generation?

Personally, I think the kids brought home a virus, and that was it! Everyone touches everything, so nobody can be spared the sickness.

Overall, this product makes sense for people who live in warm humid areas, but would an electro static filter be better?

Thanks,

Joe