It would be good to share with her articles explaining the benefits of your child getting vaccine. Also maybe you would like to find out and what is it which is makes her feel that it is unnecessary. If you are able to hear her opinions then will you be able to give her better advise. From my perspective, vaccinations is an essential and shouldnt be taken lightly.
Ask her first regarding her hesitations on getting vaccines for your children, so you will also understand where she is coming from. Then you can explain your side, including the data/facts/resources why you want to have your kids vaccinated. Most of my friends only give the DOH required vaccines. Personally, I follow our pediatrician's advise.
Allow her to explain her stance on the matter while keeping an open mind and truly listening to her. Acknowledge where she is coming from but also, if you feel strongly about it, emphasize th benefits of vaccination. Back your opinion up with data and don't speak out of emotion. Hope she'll come around!