There are no required vaccinations to visit Barcelona.
EU Citizens are entitled to the full range of health-care services in public hospitals, but you will need to present your European Health Insurance Card (enquire at your national health service before leaving home). Non-EU citizens have to pay for services. Make sure you have coverage – either with your health insurance provider at home or with a travel insurance policy.
The tap water is safe to drink in Barcelona, but it tastes awful.