From Peace Corps Wiki
All Volunteers receive comprehensive medical and dental benefits. The benefits start with coverage of vaccinations and anti-malarial prescription, which begin prior to departure. Each post has a Peace Corps Medical Officer to provide primary care. Full medical insurance during service covers 100% of primary care, hospitalization, medical evacuation, all prescriptions including birth control and dental care needs. Volunteers are also covered by workman's compensation for injuries incurred during their period of service.
Additionally, Volunteers can obtain affordable health insurance for up to 18 months following Volunteers service through an assistance program called CorpsCare. The Peace Corps pays the first month's premium and you then have the option to purchase a reasonably priced, comprehensive insurance policy to cover you and qualified dependents. More information is available in the Returned Volunteers Health Benefits section.
In most cases, Peace Corps service does not affect a Volunteer's Social Security benefits. Get answers to the most commonly asked questions by potential 50+ Volunteers.
 External Links
Medical Benefits Official US Peace Corps Website