The NDIIS data are consistent with the NIS, which has shown HPV4 coverage levels to be lower than Tdap and MCV4 coverage levels.12
The NDIIS results show the importance of missed opportunities in adolescent vaccinations and the greater reliance on the private sector for HPV4 than for Tdap and MCV4.
There are multiple reasons for HPV4 to have greater reliance on the private sector and to have lower coverage. For one, it is the most commonly refused vaccine routinely administered in the United States, and most states do not mandate HPV4 for school entry.13,
North Dakota should implement education programs for providers and parents about the safety of HPV4 and the importance of all adolescent vaccines.15,
Assessment, Feedback, Incentives, and Exchange (AFIX), a program designed to provide intervention and education to immunization providers, has been shown to help improve childhood immunization rates, and providing AFIX to adolescent providers could be a cost-effective way to educate providers and increase adolescent vaccination rates.17
Unlike Tdap and MCV4, which have been required since the 2008–2009 school year, North Dakota does not require HPV4 at middle school entry.18
School entry requirements have been shown to be effective at increasing coverage of required vaccines shortly after their adoption and could be an effective way to increase the number of females vaccinated with HPV4, as they have with the hepatitis B vaccine.19,
However, an HPV4 vaccine requirement is a politically charged issue that makes an HPV4 school entry requirement less feasible than Tdap and MCV4 school mandates.21
With the ACIP making a permissive recommendation of HPV4 for males, these issues will become even more complicated in the future.
Another barrier to being vaccinated against HPV4 is cost, which is rising due to the number and expense of vaccines. HPV4 is currently the most expensive vaccine on the market.22,
The Guide to Community -Preventive Services recommends reducing out-of-pocket expenses for vaccines by providing insurance coverage, reducing copayments, or paying for vaccines and/or administration fees.24
North Dakota has provided free vaccines to children aged 18 years and younger who are Medicaid-eligible, uninsured, American Indian/Alaska Native, or underinsured through the Vaccines for Children (VFC) program, as these vaccines were recommended by ACIP.25
However, the VFC program does not cover insured children with high deductibles or the cost of an office visit with a physician. These barriers need to be addressed to help increase vaccination coverage.
North Dakota data show that providers are missing opportunities to give adolescents all three recommended vaccines. Providers and parents should be educated about the importance of vaccination with all recommended vaccines during a visit. In a national survey, physicians identified adolescents having few preventive care visits as a barrier to immunization.26,
This barrier has become apparent as the vast majority of adolescents require two or three additional visits to receive all recommended vaccines on time.28
Increasing HPV4 vaccination coverage will require additional visits, and as the NDIIS data show, missing an opportunity to receive HPV4 vaccination when other vaccinations are given will increase the likelihood of undervaccination.
According to NDIIS data, more than one-third of females who initiated the HPV4 series and are eligible to complete the series have not received all three doses. To reduce the number of adolescents not completing the recommended vaccine series, immunization providers should review their Immunization Information System (IIS) record at each clinic visit, and the IIS and providers should incorporate reminder/recall into their practices.29,
A review of the literature on reminder/recall found it to be an effective way to increase immunizations for both children and adults in 80% of all reviewed studies.31
Eliminating missed opportunities and adding reminder/recall will improve rates, but new strategies need to be used to increase the number of adolescents initiating the vaccine series. Even if every adolescent who had received at least one dose of MCV4, Tdap, or HPV4 in North Dakota had been fully UTD, more than 10% of adolescents had not received any doses of these vaccines (). Strategies such as school immunization clinics and increased enforcement of school immunization requirements could help immunization providers reach a greater percentage of the population.32
Studies show that well-organized school-based vaccination clinics can help achieve high immunization rates.33
Collaboration between public and private immunization providers to plan and implement school vaccination clinics, along with subsidized vaccines, would help reach adolescents who are less likely to be vaccinated.
There were several limitations to this study. First, North Dakota has a small population and the study findings are not necessarily representative of other states. Second, the NDIIS contains more adolescents than census data suggest are in North Dakota. This discrepancy is due to duplicate records and because people who move to North Dakota and receive an immunization are added to the NDIIS, but the NDIIS does not currently have a way to track people who move out of state. Therefore, the NDIIS overestimates population size and, as a result, underestimates immunization rates when NDIIS population estimates are used as a denominator.
Third, we used U.S. Census numbers for the denominator to prevent downward bias in the coverage estimates. The analysis for missed opportunities did not take into account whether an adolescent had a health-care visit in which no vaccines were given or the adolescent received vaccines (e.g., influenza) and, as a result, missed all three vaccines. Older adolescents may have received Td and would not currently be recommended for Tdap, resulting in lower Tdap coverage. It is possible that some MCV4 doses were mistakenly recorded as meningococcal polysaccharide vaccine (MPSV4) and Tdap as Td, especially shortly after licensure.
Lastly, although more than 95% of immunization providers are using the NDIIS and are required by law to enter immunization information into the NDIIS for children aged 18 years and younger, it is possible that, early on, providers entered adolescent immunizations less frequently than childhood immunizations. An increase in reporting over time would lead to an exaggerated apparent increase in the vaccination rates trend.