Influenza and pneumococcal vaccines are also underutilized. Except for travelers, few patients request immunization. Therefore, the physician must initiate the process by taking a detailed immunization history, including any adverse reactions and possible egg allergies. Host-defense factors, underlying diseases, lifestyle, occupation, potential exposures, and travel must all be considered in planning appropriate immunizations. The National Childhood Vaccine Injury Act of 1988 mandates careful record keeping and reporting of adverse reactions to certain vaccines.
Immunizations are most effective when they can be completed before exposure.
However, in the case of unanticipated exposure or incomplete immunization, postexposure immunization can be very important. Active immunization achieved by the administration of a vaccine or toxoid produces longer-lasting and more complete protection than passive immunization achieved by administration of preformed antibodies. Passive immunization, however, confers more rapid protection and is particularly useful for postexposure prophylaxis. Products available for passive immunization include pooled human immune globulin, human immune globulin with high antibody titers for specific diseases, and antitoxins. Products for active immunization include vaccines produced from live microorganisms with attenuated virulence, vaccines produced from killed microorganisms or their subfractions, synthetic vaccines produced by recombinant DNA technology, and bacterial toxoids.