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...
Nội dung trích xuất từ tài liệu:
Chapter 116. Immunization Principles and Vaccine Use (Part 11) Chapter 116. Immunization Principles and Vaccine Use (Part 11) Current Controversies Even though vaccines are very safe and serious adverse events proven to bedue to licensed vaccines are rare, the recent rise in the reporting of autismspectrum disorders has led some parents of affected children to claim thatthimerosal—used as a preservative—is the cause of the problem. No study has yetimplicated thimerosal or the vaccines in which it has been used as a likely cause ofthese disorders; however, fully 50% of cases before the Vaccine InjuryCompensation Program concern autism allegedly due to mercury. In 1999,thimerosal was removed from single-dose formulations of recommendedchildhood vaccines in the United States; the exception is influenza vaccine, forwhich thimerosal-free preparations have been in short supply. There is noevidence that the frequency of autism diagnoses has changed since thediscontinuation of thimerosal use, but further observation is necessary. It isimportant to resolve these controversies, particularly because it may be difficult toensure product sterility in developing countries—where multidose vials of vaccineare most cost-effective—without the use of preservative. Disparities in vaccine coverage among the majority and minoritycommunities in the United States persist. Reasons for underimmunization includelimited access to health care, lack of insurance, assignment of a low priority topreventive measures, and insufficient knowledge about vaccines and theimportance of being vaccinated. The persistence of wild poliovirus inimmunocompromised individuals and the reversion of live poliovirus vaccine tovirulence in several communities have catalyzed debate about whether it really ispossible to eradicate poliovirus from the world (thus allowing the cessation ofimmunization) or whether the best that can be hoped for is the worldwideelimination of clinical disease, with continued routine immunization to keep therisk low. The addition of new, individually injectable vaccines to the childhoodimmunization schedule has heightened parental concerns about multiple injectionsat a single clinic visit. The continued development and testing of vaccinecombinations aim to mitigate these concerns. Even when multiple injections arerequired, providers must make every effort to administer all indicated vaccines ateach visit. Delivery of Vaccines Over the past 25 years, considerable progress has been made to ensure thatevery child in the United States is fully immunized by the time of school entry. All50 states now require immunization for school entry, and most have lawsaddressing attendance at preschools and day-care centers. Despite the dramaticimpact of immunization and of other improvements in health care on the incidenceof vaccine-preventable illness in the United States, many children still are not fullyimmunized, both in poor communities with inadequate health services and inaffluent communities where parental concern about potential adverse events mayexceed concern about now-uncommon diseases. The failure to vaccinate preschoolchildren was largely responsible for the resurgence of measles in the United Statesin 1989–1991, with >55,000 cases and >130 measles-related deaths. Outbreaks ofpertussis, mumps, and congenital rubella syndrome have occurred whereverimmunization rates among preschool children are low. While indigenoustransmission of polio, measles, and rubella has been eliminated in the UnitedStates, the risk of imported infection and spread to vaccine-naïve susceptiblepersons persists. Access to Immunization Four major barriers to infant and childhood immunization have beenidentified within the health care system: (1) low public awareness and lack ofpublic demand for immunization, (2) inadequate access to immunization services,(3) missed opportunities to administer vaccines, and (4) inadequate resources forpublic health and preventive programs. National outreach and educationalcampaigns promote parental awareness of the value of vaccination and encouragehealth care providers to use every opportunity to vaccinate the children in theircare. Handling of Vaccines Vaccines must be handled and stored with care. Attention to the entirecold chain—from storage, shelf life, reconstitution, and shelf life afterreconstitution and opening—is essential to ensuring that clients receive potentvaccines. Vaccines should be kept at 2°–8°C and, with the exception of varicellavaccine and live attenuated influenza vaccine, should not be frozen. The latter twovaccines should be kept frozen at –15°C. Measles vaccine must be protected fromlight, w ...