A vaccine is a biological preparation that provides active acquired immunity to a particular disease. The crossword solutions for the term VACCINE are SERUM (5 letters), SALK (4 letters), SABIN (5 letters), ORAL (4 letters), and FLU (3 letters). The first solution, SERUM, refers to a liquid suspension of antibodies used to provide immunity against a disease. The second solution, SALK, is a reference to Jonas Salk, the American medical researcher who developed the first successful polio vaccine in 1955. The third solution, SABIN, is a reference to Albert Sabin, the Polish-American medical researcher who developed the ORAL polio vaccine in 1961. The fourth solution, ORAL, refers to the method of administering a vaccine through the mouth. The fifth solution, FLU, is a reference to the influenza virus, which can be prevented by an annual FLU vaccine.