There is only one way to find out what their intentions were. Call them. It may be that your health insurance will not cover any claims that are caused by an illness that could have been prevented with a vaccine (especially if they cover vaccinations). However, one should think that they would mention that in the letter. On the other hand, reminders may just be a service to their customers. I got a few postcards from the health unit, reminding me when my little DD needed shots. I just trashed those and nothing ever happened. The first time, I freaked out, though, and called to let them know that she is getting her shots at the local hospital. I was told that the reminders were computer generated...