So, “boosting” your immune system is kind of a myth. Getting enough sleep and eating a balanced diet certainly optimize your healthy and help you clear infections quickly and with less severe symptoms, but the only way to NOT get sick is to have antibodies for viruses sufficiently similar to what you are exposed to. How do you get antibodies? Vaccines and wild-type infections. So the good news is that you getting sick now may prevent you getting sick in the future. Your husband may have had more illnesses in the past 10 years, or he may just have milder symptoms.

As a note, not all viruses have lifetime immunological memory, alas. So having had an illness in childhood doesn’t necessarily guarantee you won’t get it again. It’s more a matter of what you’ve had in the last 10-50 years, depending on the virus. That means it may be possible for you to get RSV again, for example. :(