The term 'Vaccine Target' refers to the specific illnesses that a vaccine is designed to protect against. In this case, the crossword solutions are FLU (3 letters), TETANUS (7 letters), ARM (3 letters), and POLIO (5 letters). Vaccines for FLU, TETANUS, and POLIO are all designed to prevent the spread of infectious diseases, while the ARM vaccine is designed to protect against a type of cancer. All of these vaccines are important for protecting public health and preventing the spread of disease.