The title is something like that. Coursera is totally free and you do not HAVE to earn a certificate. This course is through the John's Hopkins School of Public Health. You can earn a certificate. All that is required for a PreReq is knowledge of the Vaccines currently in use. (Check!). It is just beginning! Join me!
Also there are some other courses: https://www.coursera.org/courses?orderby=upcoming&cats=medicine