 [ Symptoms ] my doctor asks me to get a tetanus vaccine upon an injury when i am doubtful of acquiring tetanus  is this anti tetanus vaccine if so for how long do these vaccines are effective some say it for three months or for six months is it okay if one gets this vaccine before twenty four hours of injury [ Disease ] hiv attacks and destroys a type of white blood cell called a cd4 cell this cell is main function is to fight disease when a person is cd4 cell count gets low they are more susceptible to illnesses