Chapter 116. Immunization Principles and Vaccine Use (Part 10) An illuminating example is the case of Rotashield, a rhesus reassortant rotavirus vaccine, which was introduced for routine use in the United States in the late 1990s. Within 9 months of its introduction, cases of intussusception were reported by the CDC to be temporally associated with the administration of the initial vaccine dose. This report led first to the cessation of the vaccine's use and subsequently to its withdrawal from the market and the discontinuation of its production. The withdrawal of the vaccine in the United States made its use impossible in developing countries, where the risk of any increase in intussusception would have been dramatically outweighed by the benefit of decreased rotavirus mortality rates. It is now apparent that the susceptibility to intussception is age related, with virtually no events in children <90 days of age. Almost a decade later, a new rotavirus vaccine has been licensed in the United States and recommended for routine use beginning at ≤2 months of age. In the interim, some 4–5 million infants have died of rotavirus diarrhea in the developing world; most of these deaths could have been prevented by the original rhesus rotavirus vaccine. Vaccine components, including protective antigens, animal proteins introduced during vaccine production, and antibiotics or other preservatives or stabilizers, can certainly cause allergic reactions in some recipients. These reactions may be local or systemic, including urticaria and serious anaphylaxis. The most common extraneous allergen is egg protein derived from the growth of measles, mumps, influenza, and yellow fever viruses in embryonated eggs. Gelatin, used as a heat stabilizer, has been implicated in rare but severe allergic reactions. Local or systemic reactions (probably due to antigen-antibody complexes) can result from the too frequent administration of vaccines such as Td or rabies vaccine. Because live-virus vaccines can interfere with tuberculin test responses, necessary tuberculin testing should be done either on the day of immunization or at least 6 weeks later. Use of Vaccines in Special Circumstances Breast Feeding Neither killed nor live vaccines affect the safety of breast feeding for either mother or infant. Breast-fed infants can be immunized on a normal schedule. Even premature infants can be immunized at their appropriate chronologic age. Seroconversion in response to hepatitis vaccine at birth may be impaired in some premature infants with birth weights of <2000 g. By a chronologic age of 1 month, however, premature infants—regardless of initial birth weight or gestational age— are as likely to respond adequately to vaccines as older and larger infants. Occupational Exposure Immunization recommendations for most occupational groups remain to be developed. Specific practices for the immunization of U.S. health care workers against hepatitis B are mandated by the Occupational Safety and Health Administration. Persons employed in caring for patients with chronic diseases can transmit influenza and should be vaccinated annually, independent of age. Rubella is transmitted to and from health care workers in medical facilities, particularly in pediatric practice. Health care workers who might transmit rubella to pregnant patients should be documented to be immune to rubella; susceptible individuals should be promptly immunized. Persons providing health care are also at greater risk from measles and varicella than the general public, and those who are likely to come into contact with measles- and varicella-infected patients should be documented to be immune or be immunized. HIV Infection and Other Medical Conditions Limited studies in HIV-infected individuals have found no increase in the risk of adverse events from the use of live or inactivated vaccines. It is not surprising that immune responses may not be as vigorous in immunocompromised individuals as in those with a normal immune system; therefore, persons known to be infected with HIV should be immunized with recommended vaccines in the same manner as individuals with a normal immune system and as early in the course of their disease as possible, before immune function becomes significantly impaired. If MMR immunization is indicated, HIV-infected patients may receive the standard attenuated vaccine; if polio vaccination is required, these patients and their household contacts should receive inactivated polio vaccine. Albeit prudent, it is not necessary to test for HIV before making decisions about the immunization of asymptomatic individuals from known HIV risk groups. Live attenuated vaccines are contraindicated in other immunocompromised patients, including those with congenital immunodeficiency syndromes, those who have undergone splenectomy, and those who are receiving immunosuppressive therapy. Passive immunization with immunoglobulin preparations or antitoxins can be considered in individual cases, either as postexposure prophylaxis or as part of the treatment of established infection. Travel (See also Chap. 117) The International Sanitary Regulations allow countries to impose requirements for yellow fever and killed cholera vaccines as a condition for admission, even though the latter vaccine is not an effective public health tool. Travelers should know whether these vaccines are required for entry into the countries on their itinerary to avoid being turned back or immunized on the spot, with the inherent danger of unsafe injections in poor developing countries. Infants, children, and adults should have all routine immunizations updated before traveling, especially to developing countries, with particular attention to polio, measles, and DTaP or Tdap, depending on age. Immunity to hepatitis A and hepatitis B is advisable for travelers. Special-use vaccines (Table 116-2), including rabies, typhoid, Japanese B encephalitis, and plague vaccines, should be considered for those individuals who expect to go beyond the usual tourist routes or to spend extended periods in rural areas in disease-endemic regions. Most U.S. cities have travel clinics that maintain up-to-date epidemiologic information and can provide the appropriate vaccines. The CDC maintains a useful website for travelers (http://wwwn.cdc.gov/travel/default.aspx). . Chapter 116. Immunization Principles and Vaccine Use (Part 10) An illuminating example is the case of Rotashield, a rhesus reassortant rotavirus vaccine, which was introduced. Immunity to hepatitis A and hepatitis B is advisable for travelers. Special -use vaccines (Table 116- 2), including rabies, typhoid, Japanese B encephalitis, and plague vaccines, should be considered. rotavirus vaccine. Vaccine components, including protective antigens, animal proteins introduced during vaccine production, and antibiotics or other preservatives or stabilizers, can certainly cause