The strain of measles that caused over 55,000 cases, 130 deaths, and 1 1,000 hospitalizations in the resurgence of 1989 to 1991 no longer exists in the United States. In 1997, the number of reported measles cases was the lowest ever - a provisional total of 135 cases. All of these cases were related to imported cases, because indigenous measles transmission has apparently been interrupted. Polio, which has already been eliminated from the Americas, is likely to be completely eradicated from the world within the next 3 years.
The Childhood Immunization Initiative met all of its 1996 immunization coverage objectives, which included 90% single-antigen coverage for three DTP, three polio, one MMR, and three Hib vaccinations. These objectives were met or exceeded at the same time that the immunization schedule increased in size and complexity, and the immunization delivery system was undergoing rapid change by a shift from health department immunization clinics to private practice and managed care.
With such record low disease levels and record high vaccination coverage levels, what is left to do? Plenty! First, high coverage levels are not evenly distributed throughout the population. There is a ten percentage point gap in coverage between children living in families above the poverty level and children in families below the poverty level (81% versus 71%). Because poverty and crowding are related, pockets of need exist that pose the threat of outbreaks of vaccine-preventable disease. Second, a sustainable system to vaccinate completely each yearly cohort has not yet been built. After all, vaccinating children is not a one-time event. Rather, it is a process that must be repeated for each of the four million children born in the United States every year.
What should a sustainable, high-performance immunization delivery system look like? First, vaccination should be done in a medical home for primary care in which there is a link between patient and provider that implies accountability for ensuring timely vaccination. Such a link should be established prior to birth and should make it possible to identify children with no access to primary care and to facilitate recall systems that bring undervaccinated children to their medical home for vaccination.
Second, recommended vaccines should be available at the medical home with no need to refer children because of cost to parents or providers. Third, providers should practice in accordance with the Standards for Pediatric Immunization Practices, and, fourth, there should be information systems to tie the immunization delivery system together by monitoring immunization coverage, disease, and vaccine safety.
Some of the key components of such a system are moving into place. According to the 1997 National Immunization Survey, almost two thirds of children are vaccinated in their medical home for primary care. The cost barrier has been greatly reduced by a combination of the Vaccines for Children Program, the rise of managed care systems that cover vaccinations, and statebased insurance reforms requiring "first-dollar" coverage of vaccinations. The new 24 billion-dollar Child Health Insurance Program, which will provide insurance coverage for many cunently uninsured children, will further reduce cost and access barriers.
However, key components of the ideal system are missing, including solid patient-provider links, information systems to make immunization easier and more comprehensive, and practice patterns that cunently fall short of the Standards for Pediatric Immunization Practices.
Why do pediatricians need to put so much effort into building a robust system for the nation's children? One reason is to meet current and future prevention opportunities. The most obvious new prevention opportunities come from vaccines to control previously uncontrolled diseases. Rotavirus, pneumococcal, and meningococcal conjugate vaccines, and respiratory syncytial virus vaccines are in various stages of the vaccine development pipeline from research to practice.
Opportunities for prevention also arise from an often-neglected age group of children to protect - adolescents. In 1996, the Advisory Committee on Immunization Practices and the American Academy of Pediatrics recommended universal vaccination of adolescents with hepatitis B vaccine, tetanus, and diphtheria vaccine, and for eligible children, MMR and varicella vaccines. This set of vaccination visits at 1 1 to 12 years of age provides pediatricians with the opportunity for vaccination-related prevention as well as other health supervision procedures. Time is of the essence to protect today's adolescents before they become more difficult to reach as young adults. Each annual cohort that escapes adolescence un vaccinated will bear 150,000 hepatitis B infections, 9,000 chronic hepatitis infections, 1,350 cases of hepatitis B-associated chronic liver disease, and 1,200 hepatitis Bassociated deaths.
What are the threats to our ability to protect US children through vaccination? The most important is complacency on tñe part of providers and parents. A major concern is that complacency is fueled by low incidences of vaccine-preventable diseases. After all, few practitioners and parents can remember most vaccine-preventable diseases.
Vaccinating all children in a practice requires effort. Without special effort, many children easily slip through the primary care system until the school entry requirements identify their need for vaccination - when the vaccination is over 3 years past due. Methods to prevent such slippage are well known, and the evidence of their impact is overwhelming. Over 60 randomized controlled trials have been conducted on the ability of recall or reminder systems to improve immunization coverage levels, and virtually all have shown a strongly positive impact. However, fewer than one-infive practices use a systematic recall system to bring underimmunized children back to their practice.
Why do so few providers operate recall systems? Cost is probably not the reason, because effective systems can be as simple as a card-file tickler system. A more likely reason is that providers do not realize how many children in their practice are behind on their immunizations. Several studies have shown that providers consistently overestimate the coverage of their practice, usually by greater than 25 percentage points! A practice whose coverage is never measured will never know how well it is doing in protecting its patients. Knowing that one's practice has a problem is probably a prerequisite to implementing an effective intervention such as a recall system.
Unfortunately, relatively few private practices have had their immunization coverage assessed. Although virtually all health department immunization clinics have had systematic coverage assessments, fewer than 5% of private practices have had similar assessments. This is especially problematic because private providers vaccinate the vast majority of children in the United States.
The two most important things a practice can do to ensure timely vaccination are assessing vaccination coverage levels and operating a recall system. Tools for assessing coverage are available through the American Academy of Pediatrics, your health department's immunization program, or the National Immunization Program at the Centers for Disease Control and Prevention.
This issue of Pediatric Annals is about the immunization delivery system. It covers a broad range of topics, including barriers to vaccination, evidence-based interventions to improve coverage, making vaccination more pleasant, adolescent vaccination, vaccine safety, linkage between immunization and WIC services, immunization registries, and an update on the ever-changing vaccination schedule.
The twentieth century is supposed to be the century of the vaccine. Biotechnology is providing the ability to control an increasing number of diseases through vaccination. Will the immunization delivery system be there to meet the challenge of protecting the nation's children?