I think a dude is talking about the hygiene hypothesis, which basically says that people tend to do this thing where they don't let kids get exposed to anything when they're young (particularly parasites, as per the lovely Ms. Waterfield) which results in a naive immune system that over-reacts and predisposes you to hypersensitivity reactions later in life. This is a real thing, though the actual mechanisms involved are a bit murky. Vaccines are basically the opposite of that though, they're giving your immune system something to react to and as far as I know the hygiene hypothesis is only really talking about what your system is exposed to at a young age so having a vaccine when you're 30 is doubly irrelevant.
Things I have been taught to tell people about vaccines:
There is no good evidence they cause autism.
Just because you get a flu shot doesn't mean you won't get a cold (which isn't the same) or even the flu. There are lots of different flu strains and it mutates all the time, the shot generally protects against the most prevalent around that year.
There is NO good evidence they cause autism.
You may feel a bit groggy for a couple of days after the shot, you are taking something that causes your immune system to react, so yeah your immune system might react. In some, very very rare, cases it might even over-react, that's why they often keep you around for half an hour after certain types of vaccine. The odds of this happening are infinitesimal compared to the odds of getting badly sick if you actually get the disease.
THERE IS NO GOOD EVIDENCE THEY CAUSE AUTISM.
You might think you don't need a shot because you never get the flu, or you get over it pretty quickly, this is probably true but the thing we're more interested in with vaccines is something called 'herd immunity' that is when enough people in a given population (something like 80%) are immune to a disease, it doesn't have anywhere to live anymore and basically dies out. This is how we got rid of smallpox and polio. Point being you might get over the flu or not even notice you have it but in the mean time you might pass it on to your grandmother, or your newborn nephew, who aren't as strong and may be made very sick. No, the medical profession is not above unsubtle emotional manipulation.
You know what? Sure, vaccines cause autism. Also the CIA created AIDS to kill Freddy Mercury and end British domination of the pop charts.
That said, I often forget to get mine because as a Caucasian male aged between 18 and 50 I only go to the doctor when I can actually see bone and putting a band aid on it for two days hasn't helped.