Chapter 116. Immunization Principles and Vaccine Use (Part 11) ppsx

Chapter 116. Immunization Principles and Vaccine Use (Part 11) Current Controversies Even though vaccines are very safe and serious adverse events proven to be due to licensed vaccines are rare, the recent rise in the reporting of autism spectrum disorders has led some parents of affected children to claim that thimerosal—used as a preservative—is the cause of the problem. No study has yet implicated thimerosal or the vaccines in which it has been used as a likely cause of these disorders; however, fully 50% of cases before the Vaccine Injury Compensation Program concern autism allegedly due to mercury. In 1999, thimerosal was removed from single-dose formulations of recommended childhood vaccines in the United States; the exception is influenza vaccine, for which thimerosal-free preparations have been in short supply. There is no evidence that the frequency of autism diagnoses has changed since the discontinuation of thimerosal use, but further observation is necessary. It is important to resolve these controversies, particularly because it may be difficult to ensure product sterility in developing countries—where multidose vials of vaccine are most cost-effective—without the use of preservative. Disparities in vaccine coverage among the majority and minority communities in the United States persist. Reasons for underimmunization include limited access to health care, lack of insurance, assignment of a low priority to preventive measures, and insufficient knowledge about vaccines and the importance of being vaccinated. The persistence of wild poliovirus in immunocompromised individuals and the reversion of live poliovirus vaccine to virulence in several communities have catalyzed debate about whether it really is possible to eradicate poliovirus from the world (thus allowing the cessation of immunization) or whether the best that can be hoped for is the worldwide elimination of clinical disease, with continued routine immunization to keep the risk low. The addition of new, individually injectable vaccines to the childhood immunization schedule has heightened parental concerns about multiple injections at a single clinic visit. The continued development and testing of vaccine combinations aim to mitigate these concerns. Even when multiple injections are required, providers must make every effort to administer all indicated vaccines at each visit. Delivery of Vaccines Over the past 25 years, considerable progress has been made to ensure that every child in the United States is fully immunized by the time of school entry. All 50 states now require immunization for school entry, and most have laws addressing attendance at preschools and day-care centers. Despite the dramatic impact of immunization and of other improvements in health care on the incidence of vaccine-preventable illness in the United States, many children still are not fully immunized, both in poor communities with inadequate health services and in affluent communities where parental concern about potential adverse events may exceed concern about now-uncommon diseases. The failure to vaccinate preschool children was largely responsible for the resurgence of measles in the United States in 1989–1991, with >55,000 cases and >130 measles-related deaths. Outbreaks of pertussis, mumps, and congenital rubella syndrome have occurred wherever immunization rates among preschool children are low. While indigenous transmission of polio, measles, and rubella has been eliminated in the United States, the risk of imported infection and spread to vaccine-naïve susceptible persons persists. Access to Immunization Four major barriers to infant and childhood immunization have been identified within the health care system: (1) low public awareness and lack of public demand for immunization, (2) inadequate access to immunization services, (3) missed opportunities to administer vaccines, and (4) inadequate resources for public health and preventive programs. National outreach and educational campaigns promote parental awareness of the value of vaccination and encourage health care providers to use every opportunity to vaccinate the children in their care. Handling of Vaccines Vaccines must be handled and stored with care. Attention to the entire "cold chain"—from storage, shelf life, reconstitution, and shelf life after reconstitution and opening—is essential to ensuring that clients receive potent vaccines. Vaccines should be kept at 2°–8°C and, with the exception of varicella vaccine and live attenuated influenza vaccine, should not be frozen. The latter two vaccines should be kept frozen at –15°C. Measles vaccine must be protected from light, which inactivates the virus. Standards for Immunization Practice National standards of immunization for childhood, adolescent, and adult practice have been established to define common policies and practices for public health clinics and physicians' private offices (Table 116-4). These standards represent the most desirable immunization practices and highlight the need to distinguish between valid contraindications and conditions that are often considered to be but are not in fact contraindications (www.cdc.gov/vaccines/recs/vac-admin/downloads/contraindications_guide.pdf). . Chapter 116. Immunization Principles and Vaccine Use (Part 11) Current Controversies Even though vaccines are very safe and serious adverse events proven to be due to licensed vaccines. to infant and childhood immunization have been identified within the health care system: (1) low public awareness and lack of public demand for immunization, (2) inadequate access to immunization. and encourage health care providers to use every opportunity to vaccinate the children in their care. Handling of Vaccines Vaccines must be handled and stored with care. Attention to the entire