Adverse reactions associated with simultaneous administration of multiple vaccines to travelers

To determine the frequency of local and systemic adverse reactions following the simultaneous administration of multiple vaccines. Prospective descriptive study using a self-administered questionnaire. All patients seen in a one-year period were given the questionnaire and a stamped, return-addressed envelope to be returned three days after their clinic visits. Westchester County (New York) Department of Health Travelers' Clinic. 984 patients made 1,205 visits. 64% returned the questionnaires. The patients reported the occurrence and duration of local and systemic reactions three days after the clinic visit. Demographic data, names of the vaccines, and a description of the injection site of each vaccine were collected separately by clinic staff for each patient at each visit. 58% of the patients reported local reactions and 39.5% at least one systemic complaint. The rate of local reactions increased from 45% with 1 injection in an arm to 78% with > or = 3 (OR = 99). The rate of systemic reactions increased from 25% following the administration of 1 vaccine to 70% with > or = 5 (OR = 7). Number of vaccines did not influence duration or severity of reaction. Age and gender were not associated with frequency of reactions. Side effects for vaccination of travelers are common. Increasing the number of vaccines is associated with increasing the rates of local and systemic reactions. These reactions are generally minor and should not be a reason to withhold multiple vaccinations to patients when needed.