Whooping cough vaccine

So I was speaking with my so mom and my so last night and we were talking about the vaccine. My so seems to think although I think he's joking no one is really vulnerable to whooping cough . I've shown him videos of what it is and turns out his mom said he had it when he was a baby. That means someone in his family or that was close with him had it. So it's pushing me even more to ask the family to make sure everyone is up today with the shots. Just don't know how to approach can it without sounding like a crazy parent. Any advice