Chapter 116. Immunization Principles and Vaccine Use (Part 4)

Principles of Vaccine UseRoute of AdministrationMicrobes differ in their routes of infection, patterns of transmission, and predispositions for certain age groups. The route of vaccine administration (oral, intranasal, intradermal, transdermal, subcutaneous, or intramuscular) takes these factors into account in order to maximize protection and minimize adverse events. Vaccine development is more a pragmatic undertaking than an exact science, guided only in part by immunologic principles and shaped largely by the results of clinical trials. While vaccines can theoretically be given by any route, each vaccine has unique characteristics adapted to a particular route and, in practice, must be given...
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Chapter 116. Immunization Principles and Vaccine Use (Part 4) Chapter 116. Immunization Principles and Vaccine Use (Part 4) Principles of Vaccine Use Route of Administration Microbes differ in their routes of infection, patterns of transmission, andpredispositions for certain age groups. The route of vaccine administration (oral,intranasal, intradermal, transdermal, subcutaneous, or intramuscular) takes thesefactors into account in order to maximize protection and minimize adverse events.Vaccine development is more a pragmatic undertaking than an exact science,guided only in part by immunologic principles and shaped largely by the results ofclinical trials. While vaccines can theoretically be given by any route, eachvaccine has unique characteristics adapted to a particular route and, in practice,must be given by the licensed route, for which optimal immunogenicity and safetyhave been documented. For example, vaccines containing adjuvants are designedfor injection into the muscle mass. Mucosal administration of vaccines designedfor parenteral administration may not induce good systemic responses becausesuch vaccines do not induce mucosal secretory IgA. Administration of hepatitis Bvaccine into the gluteal rather than the deltoid muscle may fail to induce anadequate immune response, while SC rather than IM administration of DTaPvaccine increases the risk of adverse reactions. Injectable biologicals should beadministered at sites where the likelihood of local, neural, vascular, or tissueinjury is minimized. Age Because age influences the response to vaccines, schedules forimmunization are based on age-dependent responses determined empirically inclinical trials. The presence of high levels of maternal antibody and/or theimmaturity of the immune system in the early months of life impairs the initialimmune response to some vaccines (e.g., measles and pneumococcalpolysaccharide vaccines) but not to others (e.g., hepatitis B vaccine). In theelderly, vaccine responses may be diminished because of the natural waning of theimmune system, and larger amounts of an antigen may be required to produce thedesired response (e.g., in vaccination against influenza). In contrast, in some agegroups, the use of substandard amounts of antigen is sufficient for immunityinduction and reduces the risk of adverse effects (e.g., a reduced dose of diphtheriatoxoid for persons ≥7 years of age). Age-related adverse events are discussed in alater section. Target Populations and Timing of Administration Disease attack rates differ across the human life span, and the timing ofimmunization must consider these variations along with the age-specific responseto vaccines, the durability of the immune response, and the logistics for optimalidentification and vaccination of the groups at risk. Aside from immunologicparameters, many factors are involved, including demographic features; thus,vaccination programs are really as much community as individual endeavors.Schedules for immunization are ultimately derived from careful consideration ofthe many relevant variables and may ultimately depend on the best opportunitiesto reach the target groups (e.g., infancy, school entry, puberty, college enrollment,military induction, entry into the workplace). Health care workers administeringvaccines or caring for patients with vaccine-preventable diseases have a specialresponsibility to be adequately immunized themselves and to take all necessaryprecautions to minimize the risk of spreading infection (e.g., hand washingbetween immunizations or other interactions with patients). Catch-upimmunization schedules for infants and children through the age of 18 years havebeen approved by the CDC (Fig. 116-3). Figure 116-3 Catch-up immunization schedule for persons aged 4 months–18 yearswho start late or who are more than 1 month behind. 1. Hepatitis B vaccine(HepB). (Minimum age: birth) Administer the 3-dose series to those who were notpreviously vaccinated. A 2-dose series of Recombivax HB is licensed for childrenaged 11–15 years. 2. Rotavirus vaccine (Rota). (Minimum age: 6 weeks) Do notstart the series later than age 12 weeks. Administer the final dose in the series byage 32 weeks. Do not administer a dose later than age 32 weeks. Data on safetyand efficacy outside of these age ranges are insufficient. 3. Diphtheria andtetanus toxoids and acellular pertussis vaccine (DTaP). (Minimum age: 6weeks) The fifth dose is not necessary if the fourth dose was administered at age≥4 years. DTaP is not indicated for persons aged ≥7 years. 4. Haemophilusinfluenzae type b conjugate vaccine (Hib). (Minimum age: 6 weeks) Vaccine isnot generally recommended for children ...