- There is a direct correlation between the rates of infant immunization in a community and the rates of vaccine-preventable diseases.
- The complexity of the immunization schedule has posed challenges for both families and providers.
- Missed opportunities present a significant barrier to adequate immunization by the age of 2 years.
- The personal and philosophical beliefs of the parents are the most influential in the vaccination decision.
Immunization programs have had a dramatic impact on reducing the number and severity of communicable disease outbreaks. Such diseases as smallpox and polio have been completely eradicated in the United States. However, many other vaccine-preventable diseases persist and in some cases have increased in prevalence because of lowered immunity in the general population. Childhood vaccines do much to provide lifetime immunity to certain diseases, but for other diseases, such as pertussis, additional doses of vaccine are now recommended to protect individuals with waning immunity.1 Experience has taught us that there is a direct correlation between the rates of infant immunization in a community and the rates of vaccine-preventable diseases.
A national goal of Healthy People 2010 is to “achieve and maintain effective vaccination coverage levels for universally recommended vaccines among young children.”2 The specific goal is for 90% of all children to have completed the recommended series of immunizations by age 2 years. Vaccination rates of 90% are generally sufficient to prevent the spread of communicable disease via “herd immunity.”
Herd immunity is conferred when most of the individuals within a community have developed immunity either from receiving a vaccination against a particular disease or from having contracted the disease. In communities with herd immunity, vulnerable individuals are protected because the majority of persons with whom they come into contact are immune to and incapable of spreading the disease. Effective vaccination programs are important in raising the levels of herd immunity in communities.
Unfortunately, as we near the target year 2010, studies reveal that we as a nation are falling short of this important goal. Nurse practitioners and physician assistants have a unique opportunity to assure immunization adequacy in their patients. Many people may be unaware of the vaccine recommendations for their age group or may not have had access to vaccine services or information. In addition, adult patients and parents of young children may have difficulty making sense of the conflicting stories about vaccine safety. To reach the goal of providing herd immunity in communities requires diligence in using each and every patient encounter as an opportunity to determine vaccination status.3
A number of factors have been identified as impacting immunization rates in the United States. Kimmel et al have categorized these barriers as systems barriers, provider barriers, and parent or patient barriers.4
Systems barriers
Barriers to immunization that involve health-care organizations and economics are considered systems barriers. Some of the factors that impact national immunization rates include incomplete use of a centralized vaccine registry, lack of a universal vaccination record, vaccine shortages, vaccine costs, and complexity of the immunization schedule.
Centralized vaccination registries: Immunization information systems (IIS) or immunization registries have been federally funded in the United States since 1994.5,6 For the health-care provider, an IIS can be a complete record of the vaccines previously received by a patient, not just through a specific practice but from all other sources, including health department clinics and other providers. That information can assist the PA or NP in determining if vaccines should be offered while the individual is in the office. This can reduce missed opportunities for administering vaccines during nontraditional visits, such as a “sick” or urgent-care appointment, and avoid the need to reschedule an appointment to receive vaccines.
IIS can also benefit patients and parents by providing an accurate, accessible vaccine record. Many individuals are unsure about when a vaccine was last given, the type of vaccine received, and when additional vaccines are needed.
Most states have a centralized vaccine registry system in place, but a number of factors can interfere with its effective utilization. For example, the value of an IIS is limited by the number of providers who regularly and accurately upload vaccination information into the system. Subsequently, shortages in office staff may cause delays in information retrieval. When an accurate, up-to-date record is unavailable, patients can receive duplicate, invalid, or mistimed vaccine doses, or they can miss needed vaccines altogether. Many state registries record only vaccines given to children and may not store information on adults.
Vaccine shortages: Limited amounts of vaccine are another systems barrier that can impact vaccination rates. Reasons for vaccine shortages include dwindling numbers of manufacturers, delays caused by the manufacturing process, and situations in which demand exceeds supply.
The number of licensed vaccine manufacturers in the United States continues to decrease as many companies choose to develop more lucrative vaccines or move their operations overseas. A number of manufacturers have ceased production of some or all vaccines because of their lack of profitability or the high costs associated with vaccine liability.
When vaccines have only a single manufacturer, that manufacturer may from time to time struggle to keep up with demand and shortages can develop. Shortages can also be precipitated by changes in vaccine requirements, e.g., to include an additional age cohort that needs to receive the vaccine. In addition, newer vaccines may gain popularity very quickly, and the supply may be depleted before additional vaccine can be manufactured. In 2001, eight of the 11 universal childhood vaccines were either unavailable or in short supply.7
Several vaccines for adults have also been in short supply, such as the combined tetanus, diphtheria, and pertussis (Tdap) vaccine and the herpes zoster, or shingles, vaccine. When vaccines are unavailable, patients may reschedule their appointment to receive the missing vaccines or they may delay receiving any vaccines until the entire series is available. In many cases, individuals either fall behind or forget to return once the vaccines are available.
Socioeconomic factors have been a primary concern in assuring that all children have access to vaccines. The rates of uninsured children are at historic highs. Even when families are covered by an insurance program, deductibles or co-pays may be very high or coverage for vaccines may be incomplete. National programs, such as Vaccines for Children (VFC), provide vaccines for uninsured or underinsured children, but few programs provide free vaccines to adults.
Appointments for well-child examinations are a traditional time for vaccine administration during the first two years of life. Some families exceed the allowance for well-child care or immunizations before completing all the recommended visits or vaccines. This may result in families' postponing vaccines because of cost. Older children and adults are less likely to receive well-care examinations and may not see a primary-care provider for years except for acute-care or urgent-care visits. Unless the NP or PA asks about vaccine status at these visits, individuals may not receive needed vaccines.
Costs: The VFC program has been important in providing vaccines to children who are Alaskan Natives, American Indian Natives, Medicaid-eligible, or without insurance coverage. However, VFC and 317 other programs face funding challenges and at times have had insufficient monetary support to cover all recommended vaccines. In their study, Smith and colleagues found that immunization rates among VFC-eligible children who received all recommended vaccines from their medical home were as likely to be up to date as non-VFC-eligible children who had a medical home.7 VFC-eligible children who lacked a medical home or who had incomplete insurance coverage for vaccines were less likely to be adequately immunized.
In order to provide all the recommended vaccines, a health-care practice must make a significant financial investment in supplies and in knowledgeable personnel who can administer the injections. Some providers are unable to recover their costs. Providers can also incur financial losses if privately purchased vaccines are lost as a result of waste or because of refrigerator or other storage malfunction.
Immunization schedule: Another systems barrier is the complexity of the immunization schedule. Over the past 25 years, the number of childhood vaccines has more than doubled. In the early 1980s, there were 11 recommended childhood vaccines to prevent seven diseases.8 In 2007, the number of diseases preventable by childhood vaccines had increased to 16. Children may receive as many as 24 vaccines during the first two years of life. The complexity of the immunization schedule has posed challenges for both families and providers.
Although a number of vaccines are required by schools and day-care facilities, there are other vaccines that are recommended but not required. Oftentimes, newer vaccines that are recommended but not required are unavailable through the VFC program and may not be covered by individual insurance plans. Some insurance companies were initially reluctant to reimburse for the Tdap vaccine but would reimburse for the tetanus and diphtheria (Td) vaccine, leaving many adults and adolescents at risk of contracting pertussis.
Vaccine recommendations in the United States are made by the Advisory Committee on Immunization Practices (ACIP). This group includes representatives from the American Academy of Pediatrics and the American Academy of Family Physicians. ACIP provides recommendations regarding vaccines and the timing of their administration to the CDC, which issues immunization schedules for children as well as adults each year. The infant immunization schedule was developed so that children could receive most of the required as well as recommended vaccines by age 2 years. A single harmonized schedule of recommended childhood vaccines allows for consistency across different medical disciplines. The schedule provides age ranges (0-6 years, 7-18 years, adults) at which vaccines can be administered as well as a catch-up schedule to get children who have fallen behind to receive all vaccines by age 2 years. NPs and PAs can refer to the CDC Web site for the most current vaccine recommendations for each age group in their practice. Despite recommendations from the ACIP and the CDC, some health-care providers do not adhere to the schedule because of personal or philosophical differences.
Provider barriers
Support from the health-care provider and clinic staff is an important predictor of childhood immunizations.9 This support may take the form of educating the family on the importance of immunizations and alleviating fears about potential benefits and risks. Because the immunization schedule is so complex, office staff members sometimes have difficulty interpreting the vaccine record of an individual patient. This can lead to vaccines being overlooked or missed or to the administration of invalid doses.
Missed opportunities: One of the most significant provider-related barriers impacting immunization rates is missed opportunities,10 i.e., those health-care encounters in which a child failed to receive a required immunization for which he was eligible. Missed opportunities include visits to the clinic by the family for a sick or urgent-care appointment; few illnesses prevent a child from receiving a vaccine. In addition, children or adults accompanying another child or family member to an appointment could receive vaccines if the determination is made that they are missing recommended vaccine doses.
Missed opportunities present a significant barrier to adequate immunization by the age of 2 years. In a study led by Bardenheier, the majority of children who were not up to date on vaccines were behind because of missed opportunities. The authors found that underimmunization at 3 months of age was a strong predictor for remaining underimmunized by age 2 years.11 In another study, delayed receipt of the vaccines due at 2 months was a strong risk factor for lack of age-appropriate vaccines at age 2 years.12
The well-child exams done when children are 9 months old and 18 months old are times when those who are behind in their vaccines could be brought up to date. In attempting to identify reasons for incomplete immunizations in 2-year-olds, one study found that 46% of such patients had failed to receive the fourth dose of the diphtheria, pertussis, tetanus (DPT) vaccine at the 18-month visit.13 Therefore, using the 18-month well-child examination as an opportunity for providing vaccines can significantly reduce the number of children incompletely vaccinated at 2 years of age. In addition, asking about immunization status at each and every office visit will ensure that children and adults have received all needed vaccines.
Combination vaccines are useful for administering multiple vaccines with a single injection. This approach also reduces the pain associated with receiving several injections at the same visit. Combination vaccines have been in use for years. Vaccines such as the measles, mumps, rubella (MMR) and the DTap vaccines are familiar to clinicians. A number of other vaccines are available in combination, including one for hepatitis A and hepatitis B and a vaccine that contains MMR and varicella.
Vaccines and the immune system: Some parents and health-care providers are concerned about the increasing number of vaccines being administered to very young children. Parents may be concerned that the infant's immune system is inadequately developed to handle all the vaccines administered over the first two years of life and that receiving so many vaccines could potentially overwhelm the child's immune system. However, studies have not demonstrated that the vaccines weaken the immune system. In fact, the number of antigens to which a child's immune system is exposed through the recommended vaccines is actually lower than the number of antigens individuals encountered 40 or more years ago from naturally occurring infections.14 Some parents and others may believe that the risks associated with a vaccine are greater than the potential of contracting the rarer diseases, such as diphtheria or polio.
Cost factors: Financial and cost factors can influence the availability and promotion of vaccines in private practices. The cost of administering privately purchased vaccines is prohibitive for some providers who are poorly reimbursed for vaccines by insurance carriers and managed health-care plans. The purchase of vaccines is the highest cost incurred by pediatric offices, higher even than personnel costs. Yet some vaccines are reimbursed at a price that does not compensate the health-care office for vaccine administration costs, including those associated with the storage, supply, and personnel necessary to administer vaccines. Economic losses associated with vaccines can result from the previously noted storage problems, expiration of the vaccine before it is administered, and coding or billing errors.
Parental factors
Although NPs and PAs have a voice in the decision to vaccinate a child, the personal and philosophical beliefs of the parents are the most influential in the vaccination decision. Mothers are known to be instrumental in whether children are up to date with vaccines. Addressing maternal concerns and fears regarding vaccines is an important factor in the timeliness of vaccine receipt by preschool-aged children.15 Several factors can influence a parent's decision to vaccinate. Among them are his or her understanding of the risks and benefits of vaccines, perceived threat from the diseases they will prevent, and information that the family has received from the media or other influences. The information regarding vaccines can be very confusing for parents. Many reputable-looking Web sites are actually antivaccine sites. The quality of the information from these sites is suspect.
There has been much publicity in recent years regarding possible links between vaccines and the development of autism or other neurologic disorders. This publicity, along with other actual, unsubstantiated, or disproved vaccine safety concerns, has resulted in parental fears and concerns regarding the safety of vaccines.16 Such fears may cause families to delay immunizations or to decline them altogether.
Adverse outcomes: In 1999, concerns were raised about a causal link between the administration of vaccines containing the preservative thimerosal and the development of autism and/or other neurologic conditions. Since the release of that first report, however, several other researchers have conducted studies to evaluate that relationship. No epidemiologic evidence for a causal association between thimerosal and the development of autism could be identified.17-22
For many families, the fear of adverse reactions or harm from vaccines outweighs concerns of the child's contracting the disease. Some families may still believe that the immunity derived from actually having the disease is superior to the immunity that develops in response to the receipt of a vaccine.23 Contracting some diseases, such as varicella, generally provides lifetime immunity.
WIC: Enrollment in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) was found to be correlated with on-schedule receipt of vaccines by young patients.11,12, 24-27 Children whose mothers participated in the WIC program during pregnancy and continued utilizing WIC services after the birth of their child were more likely to be up to date on vaccines than children from families that did not participate in WIC.
Conclusion
A number of factors affect vaccination rates of children and adults. Many individuals do not know they are missing recommended vaccines that could protect them against preventable diseases. NPs and PAs can improve immunization rates by asking about vaccine status at each and every patient encounter and providing education on the vaccines recommended for the age of the individual. Many people may not be aware of newly available vaccines and will look to you for advice. You may also find yourself explaining and clarifying benefits and risks of vaccines. There is much misinformation about the safety and efficacy of vaccines, and you can be instrumental in assisting patients in receiving needed vaccines and improving the health of your community.
Dr. Stevenson is division director of the Salt Lake Valley Health Department in Salt Lake City and a clinician in an urgent-care setting.
References
1. Centers for Disease Control and Prevention. Recommended adult immunization schedule—United States, 2009. MMWR. 2009;57(53):Q-1-Q-4.
2. U.S. Department of Health and Human Services. Healthy People 2010: Understanding and Improving Health. 2nd ed. Washington, D.C.: U.S. Government Printing Office; November 2000.
3. Luman ET, Barker LF, Shaw KM, et al. Timeliness of childhood vaccinations in the United States: days undervaccinated and number of vaccines delayed. JAMA. 2005;293:1204-1211.
4. Kimmel SR, Burns IT, Wolfe RM, Zimmerman RK. Addressing immunization barriers, benefits, and risks. J Fam Pract. 2007;56(2 Suppl Vaccines):S61-S69.
5. Bartlett DL, Washington ML, Bryant A, et al. Cost savings associated with using immunization information systems for Vaccines for Children administrative tasks. J Public Health Manag Pract. 2007;13:559-566.
6. Hinman AR, Urquhart GA, Strikas RA; National Vaccine Advisory Committee. Immunization information systems: National Vaccine Advisory Committee progress report, 2007. J Public Health Manag Pract. 2007;13:553-558.
7. Smith PJ, Santoli JM, Chu SY, et al. The association between having a medical home and vaccination coverage among children eligible for the Vaccines for Children program. Pediatrics. 2005;116:130-139.
8. Hillenbrand KM. What is going on with vaccines: keeping up with the childhood immunization schedule. J Public Health Manag Pract. 2007;13:544-552.
9. Gore P, Madhavan S, Curry D, et al. Predictors of childhood immunization completion in a rural population. Soc Sci Med. 1999;48:1011-1027.
10. Wood D, Schuster M, Donald-Sherbourne C, et al. Reducing missed opportunities to vaccinate during child health visits. How effective are parent education and case management? Arch Pediatr Adolesc Med. 1998;152: 238-243.
11. Bardenheier BH, Yusuf HR, Rosenthal J, et al. Factors associated with underimmunization at 3 months of age in four medically underserved areas. Public Health Rep. 2004;119:479-485.
12. Brenner RA, Simons-Morton BG, Bhasker B, et al; NIH-D.C. Initiative Immunization Working Group. Prevalence and predictors of immunization among inner-city infants: a birth cohort study. Pediatrics. 2001;108: 661-670.
13. Boulianne N, Deceunick G, Duval B, et al. Why are some children incompletely vaccinated at the age of 2? [French]. Can J Public Health. 2003;94:218-223.
14. Offit PA, Quarles J, Gerber MA, et al. Addressing parents' concerns: do multiple vaccines overwhelm or weaken the infant's immune system? Pediatrics. 2002;109:124-129.
15. Luman ET, McCauley MM, Shefer A, Chu SY. Maternal characteristics associated with vaccination of young children. Pediatrics. 2003;111:1215-1218.
16. Freed GL, Clark SJ, Hibbs BF, Santoli JM. Parental vaccine safety concerns. The experiences of pediatricians and family physicians. Am J Prev Med. 2004;26:11-15.
17. Taylor B, Miller E, Farrington CP, et al. Autism and measles, mumps, and rubella vaccine: no epidemiological evidence for a causal association. Lancet. 1999;353:2026-2029.
18. Confavreux C, Suissa S, Saddier P, et al; Vaccines in Multiple Sclerosis Study Group. Vaccinations and the risk of relapse in multiple sclerosis. N Engl J Med. 2001;344:319-323.
19. Madsen KM, Hviid A, Vestergaard M, et al. A population-based study of measles, mumps, and rubella vaccination and autism. N Engl J Med. 2002;347:1477-1482.
20. Stehr-Green P, Tull P, Stellfeld M, et al. Autism and thimerosal-containing vaccines: lack of consistent evidence for an association. Am J Prev Med. 2003;25:101-106.
21. Hviid A, Stellfeld M, Wohlfahrt J, Melbye M. Association between thimerosal-containing vaccine and autism. JAMA. 2003;290:1763-1766.
22. Parker SK, Schwartz B, Todd J, Pickering LK. Thimerosal-containing vaccines and autism spectrum disorder: a critical review of published original data. Pediatrics. 2004;114:793-804.
23. Chen RT, Hibbs B. Vaccine safety: current and future challenges. Pediatr Ann. 1998;27:445-454.
24. Cortese MM, Diaz PS, Samala U, et al. Underimmunization in Chicago children who dropped out of WIC. Am J Prev Med. 2004;26:29-33.
25.Luman ET, McCauley MM, Shefer A, Chu SY. Maternal characteristics associated with vaccination of young children. Pediatrics. 2003;111(5 Part 2):1215-1218.
26. Morrow AL, Rosenthal J, Lakkis HD, et al. A population-based study of access to immunization among urban Virginia children served by public, private, and military health care systems. Pediatrics. 1998;101:E5.
27. Zúñiga de Nuncio ML, Nader PR, Sawyer MH, et al. A prenatal intervention study to improve timeliness of immunization initiation in Latino infants. J Community Health. 2003;28:151-165.
All electronic documents accessed September 23, 2009.