I Am A 65-year Old Female. It Seems That I

I am a 65-year old female. It seems that I keep getting head colds or sinus infections. Almost every time I'm around my grandkids or other little kids. Is there something I should take to strengthen my immune system? I had both the annual flu shot and pneumococcal vaccine last November. My symptoms typically last about a week, so I guess pretty typical for a virus.