A medical breakthrough is a major advancement in the field of medicine, often resulting in a new treatment or CURE for a previously incurable disease. In this crossword, two solutions are provided: 'VACCINE' (7 letters) and 'CURE' (4 letters). A VACCINE is a biological preparation that provides immunity to a particular disease, while a CURE is a complete or permanent solution to a health problem. Both vaccines and cures can be considered medical breakthroughs, as they provide new ways to prevent or treat diseases.