Adult Immunization: What Can We Learn from the Childhood Immunization Program?

Abstract

Over the past year, the Infectious Diseases Society of America has been developing principles on strengthening adolescent and adult immunization coverage. A summary of those principles is published in this issue of Clinical Infectious Diseases [1], and the complete document is available in the online edition of the journal [2]. We wish to provide personal perspectives on the issue of adult immunization that are based on our collective 26 years of experience directing the immunization program at the Centers for Disease Control and Prevention (CDC; 1977–1987 for A.R.H. and 1988–2004 for W.A.O.). Childhood immunization is one of the great success stories of public health and clinical medicine [3]. Immunization levels are at record highs, and levels of vaccine-preventable diseases are at record or near-record lows [4, 5]. Historically, when new vaccines have been introduced and recommended for routine use in children, acceptance and coverage have increased rapidly. In contrast, immunization levels among adults for vaccines that are universally recommended for ⩾1 age group are much lower (<70% for pneumococcal polysaccharide vaccine and influenza vaccine among persons aged ⩾65 years), and pneumonia and influenza continue to be leading causes of death for senior citizens, even though the vaccines have both been recommended for routine use for >30 years [6,7–8]. Adults aged <65 years with high-risk conditions should receive annual influenza immunization. Few do. In addition, racial/ethnic disparities in children's vaccination coverage have been largely eliminated but persist among adults [9,10–11]. Why are these outcomes so different, and what can we learn from the childhood immunization experience that can be used to improve adult immunization in the United States? This seemingly rhetorical question becomes more relevant as more vaccines are developed and recommended for use in adults as well as in children. In our minds, there are at least 6 (interrelated) characteristics of childhood immunizations that set them apart from adult immunizations. Each is considered briefly below. For both children and adults, the vast majority of immunizations are delivered in the private sector, usually in a physician's office [12,13–14]. However, there is an important role for health department clinics in childhood immunization. Such clinics administer ∼15% of total childhood immunizations and are a safety net for children who are not served in the private sector for a variety of reasons, such as the inability to pay for vaccines and vaccination. There is not as well-organized of a safety net for adults. In addition, the Vaccines for Children (VFC) program, in which 45,000 provider sites participate, provides free vaccines from state and local health departments to individual providers for eligible children. This establishes and maintains a close tie between the clinical care and public health systems. Each provider who receives free vaccines must agree to an annual visit by VFC representatives, at which time public health staff can work with the provider office to make recommendations for improving their childhood immunization efforts (the VFC program is described further in the next section). No such mechanism exists for adult immunization. The cost of immunization bears an obvious relationship to the use of vaccines, and removal of financial barriers has been shown to be an effective means of improving vaccine coverage levels [15]. Although traditional vaccines (i.e., those in widespread use before 1990) were quite inexpensive, newer vaccines carry higher costs. The cost of vaccines to fully immunize a child against 7 diseases in 1985 was ∼$45 in the public sector; in 2006, the cost was ∼$1180 to protect against 16 diseases. For senior citizens, the cost of vaccines in 1987 was ∼$6 (for pneumococcal polysaccharide and influenza vaccines); in 2006, the cost of these vaccines was ∼$25. The inclusion of herpes zoster vaccine raises the cost to ∼$133 (Lance Rodewald, National Center for Immunization and Respiratory Diseases, CDC; personal communication). Three primary mechanisms exist to finance immunization efforts: the government, private insurers, and the individual (i.e., through out-of-pocket payments) [16]. In 2005, government purchases (local, state, and federal) accounted for 54% of all childhood vaccine doses distributed. The VFC program in an entitlement to free, government-purchased vaccine for all children who are uninsured, who are covered by Medicaid, or who are American Indian/Alaska Natives. Thus, except for those who are underinsured (i.e., who have insurance that does not cover immunization), the cost of vaccines is not a barrier to children or adolescents. Most private insurance plans cover childhood immunization. Section 317 of the Public Health Service Act provides support for immunization activities through state and local health departments (including purchase of vaccine), and health departments typically provide vaccines to anyone who comes, whether insured or not. For adults aged <65 years, there is no entitlement program corresponding to VFC, and vaccines are recommended for many of these individuals—including annual influenza immunization for persons aged ⩾50 years, boosters every 10 years with tetanus and diphtheria toxoids, and a single booster dose of acellular pertussis vaccine combined with tetanus and diphtheria toxoids for all adults aged <65 years [17, 18] Most private insurance plans cover adult immunizations, but ∼14% of adults aged <65 years are uninsured and, thus, would have to pay out-of-pocket for immunizations. Although Section 317 funds can legally be used to support adult immunization activities, priority has always been given to assuring that children are immunized. Virtually all adults aged ⩾65 years are covered by Medicare, which reimburses for pneumococcal and influenza vaccines (and hepatitis B vaccine for those with end-stage renal disease). However, the new zoster vaccine will only be covered by Medicare Part D [19]. Consequently, the cost of vaccination may be a barrier to a significant proportion of the elderly population who do not participate in Part D. The cost barrier may not be limited to vaccine costs. Because there are few public health clinics that provide vaccines to adults, persons usually must seek immunization in the private sector and, when they do, must also pay administration fees. Vaccines and toxoids, such as those for measles, polio, and tetanus, are highly effective (>90%) against diseases that are characteristic and easily recognized by parents, as well as by health care providers. In contrast, the current pneumococcal polysaccharide and influenza vaccines are only ∼70% effective in protecting against disease caused by the serotypes included in the vaccine, and there are many other causes of pneumonia and influenza-like illness in adults. The vast majority of the American public is both aware of and supportive of childhood immunization. Society as a whole is also supportive of this endeavor, as is manifested by the fact that all 50 states have enacted (and enforce) immunization requirements for entry to day care or schools [20, 21]. There is a national vaccine injury compensation program that involves vaccines recommended universally for children. Similar expectations or requirements do not exist for adult immunization, with the exception of some occupational requirements (e.g., the military). The fact that <70% of Medicare recipients receive influenza or pneumococcal vaccines, even when there is no financial barrier to immunization, reflects the lower expectations for adults. Although adults are covered under the National Vaccine Injury Compensation Program if they are injured by vaccines that are also recommended for children (e.g., influenza), there is no compensation for vaccines that are recommended solely for adults (e.g., pneumococcal polysaccharide and zoster vaccines). During the 2003–2004 influenza season, >150 deaths among children were attributed to influenza, resulting in headlines across the nation and a widespread concern about influenza in children [22,23–24]. In contrast, the annual influenza toll of >30,000 deaths among the elderly population receives little attention. Studies show that the physician is the most trusted source of information about immunization. Pediatricians and family physicians are major advocates of childhood immunization, both in their offices and in public policy settings. Well child care is a major part of pediatric practice; “well adult care” is not as big a part of the work of most clinicians caring for adults. In contrast to the many visits for well child care built into pediatric practice, routine well adult visits are infrequent. Because pneumococcal and influenza vaccines are not as effective as most childhood vaccines, and because many of the clinical manifestations of these infections are similar to syndromes caused by other agents that are not preventable by use of these vaccines, physicians who treat adults may not recommend them strongly for their patients. In each state, there is a public health department-;sponsored immunization program devoted to assuring high levels of immunization among children [25]. Activities include assessing immunization levels at both community and practice levels, promoting immunization, and conducting surveillance for vaccine-preventable diseases, with response to their occurrence. Immunization coverage of preschool children is measured annually through the National Immunization Survey, and state and major urban area coverage rates are published, so those areas can determine how well they are performing in comparison with other areas. States usually take these coverage rates seriously, and low-level coverages have been leveraged by some states to obtain additional resources. Few states have comparable programs for adult immunization, and there is no National Immunization Survey for adults. Forty-nine states are developing Immunization Information Systems (IIS, Immunization Registries) to compile comprehensive immunization information for all children in the state, as well as to provide services (such as reminders) that the subject is due for a vaccination or recalls that a vaccination is overdue. As of 31 December 2005, a total 56% of US children aged <6 years were participating in IIS (G. Urquhart, National Center for Immunization and Respiratory Diseases, CDC; personal communication). Although most IIS are capable of including immunization information on adolescents and adults, it is estimated that <25% of adults >50 years of age are currently enrolled in the IIS. The CDC provides national leadership on immunization of children, adolescents, and adults, but their resource emphasis (both internal and external) has been on childhood immunization. Appropriations under Section 317 have not kept pace with the increasing cost and number of childhood vaccines; this has precluded placing added emphasis on adult immunization. The contrasts between how well we, as a nation, have done with childhood immunization and how poorly we have done with adult immunization are striking and give clear indications as to what we should do. In 2005, the National Vaccine Advisory Committee (NVAC) called for, among other things, expanded funding (through Section 317) to support adolescent and adult immunization programs, including vaccine purchases; promotion of “first-dollar” insurance coverage for immunization efforts; assurance of adequate reimbursement for administration of vaccines; and expanded discussions about the need, desirability, and feasibility of a variety of approaches (e.g., a Vaccines for Adults or Vaccines for All program) to ensure that adults have access to vaccines, even if they do not have insurance [26]. Also, in 2005, the Partnership for Prevention convened a panel of immunization experts and issued the document Strengthening Adult Immunization: A Call to Action [27], which noted 6 steps that they considered to be effective, affordable, and politically feasible. Four of these were (1) to purchase and distribute influenza vaccine for uninsured adults, (2) to ensure first-dollar coverage for influenza and pneumococcal vaccines in the Federal Employee Health Benefit Program, (3) to expand Section 317 of the Public Health Service Act to address adult immunization needs; and (4) to launch a national campaign to educate Americans about the value of adult immunization. The Partnership for Prevention recommendations have been endorsed by the American Medical Association, the American Academy of Family Physicians, the American College of Preventive Medicine, the Association of State and Territorial Health Officials, the National Association of County and City Health Officials, and the American Public Health Association. These separate but complementary sets of recommendations, as well as IDSA principles, give clear guidance for action. From our perspective, minimum actions include an increase in Section 317 appropriations, with an earmark for adult immunizations; establishment and/or enhancement of public sector infrastructure for promoting/coordinating adult immunizations; assurance of adequate reimbursement for vaccine administration; measurement of and publicity for adult immunization coverage rates, by state and locality, to track progress and to identify good performers and areas that need improvement; and establishment of a culture of immunization among those who provide care to adults. In addition to these minimum actions, we believe that a Vaccines For Uninsured Adults Program would be highly beneficial. We know what to do. We just have to do it. Potential conflicts of interest. W.A.O. has received recent research funding from Chiron Foundation/Novartis, Chiron, Merck, Sanofi-Pasteur, Enorium (formerly Dynport), GlaxoSmithKline, and the New Zealand Ministry of Health; is on the board of directors for Sabin Vaccine Institute, Every Child by Two, and the National Foundation for Infectious Disease; and is a member of the 317 Coalition for Vaccine Finance. A.R.H.: no conflicts.

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