I'm sorry to hear about your friend's son.

And you're right, the risk of an ill effect is non-zero. That doesn't mean it's not safe, though. If our definition of safe means absolutely zero risk, then almost nothing is safe. Relative to most medical procedures, vaccines are incredibly safe.

I'm going to continue telling everyone I know that they should vaccinate their children because that position is supported by the best available science, and because the alternative is definitely not safe.