Can any doc explain if vaccines still work if you took it a long time ago?

Depends: Some vaccines, typically those for viral illnesses can provide lifelong immunity. Some vaccines, like those against bacteria have a more short term benefit and may require boosters. The MMR (viral) is thought to provide 85% of patients with lifelong immunity with 1 dose after 1 yr of age. The vaccines for pertussis, tetanus and diphtheria need boosters for long term benefit.

Yes: Vaccines are used to create immunity to disease using the bodies natural defenses. It is rare for vaccines to fail. Prior vaccines will not cause failures nor will are they more likely to fail over time. It used to be thought that vaccines give lifelong immunity but no longer. Please keep your vaccinations up to date. Check with your doctor as to which ones you need.