Adult immunization policies in advanced economies: vaccination recommendations, financing, and vaccination coverage

Vaccines are one of the most cost-effective strategies to prevent infectious diseases among children, adolescents, and adults. Globally, vaccination saves an estimated 2–3 million lives each year. (WHO and UNICEF 2005) Many developed countries have robust child vaccination programs, and initiatives, such as the Expanded Programme on Immunisation and the Global Alliance for Vaccines and Immunisation, are helping developing countries build childhood immunization infrastructures and introduce new vaccines. (Levine et al. 2011) In contrast to the importance placed on childhood vaccination, less attention has been paid to adult immunization, even in developed countries with strong public health infrastructures. (Advisory Council for the Elimination of Tuberculosis and Advisory Committee on Immunization Practices 1996; Lang et al. 2011; Levine et al. 2011).

Vaccinating adults against infectious diseases is important because adults can be carriers of infectious diseases to the susceptible, and immunity from childhood immunizations wanes with age, leading to disease outbreaks such as pertussis in the United States. (Zepp et al. 2011) Additionally, many vaccines are most effective among the healthy, and it is good clinical practice to vaccinate healthy adults before they develop chronic conditions that are contraindications for vaccination or make vaccines less effective. Some vaccine-preventable diseases can become more severe with increasing age. Some adults were not vaccinated as children. Last, with increasing globalization, more and more people travel across borders and are susceptible to infectious diseases that are not endemic in their home country.

Successful childhood vaccination programs contain policies recommending vaccination, effective funding mechanisms, and routine vaccination coverage assessment. To better understand adult vaccine policies, we conducted a survey in 2010–2011 of 33 advanced economies around the world as defined by the International Monetary Fund in 2009. (International Monetary Fund October 2009) We asked about adult vaccination schedules, vaccine recommendations, vaccine funding mechanisms, and vaccination coverage availability and estimates. We also investigated the associations of having adult vaccine policies in place with the population size, per capita gross domestic product (GDP), per capita expenditure on health, and out-of-pocket spending on health.

To understand the prior literature on vaccine recommendations and vaccine coverage for adults in developed countries, we performed a PubMed/MEDLINE and Internet search for adult vaccine schedules and/or recommendations. The majority of the literature presented influenza vaccination coverage, with a few papers presenting vaccination coverage for other vaccines such as pneumococcal, hepatitis B, and tetanus vaccines. (Bader and Egler 2004, 2009; Beytout et al. 2004; Blank et al. 2009; de Miguel 2006; del Corro et al. 2009; Gavazzi et al. 2007; Kwong et al. 2007; Leggat et al. 2009; Montrieux et al. 2002; Nielsen et al. 2009; Noakes et al. 2006; Pebody et al. 2008; Sammarco et al. 2004; Schenkel et al. 2008; Stuck et al. 2007; van Houdt et al. 2009) We were unable to identify published literature that discussed a comprehensive adult vaccine schedule and adult vaccine financing in developed countries. To determine the denominator, we used the International Monetary Fund’s (2009) classification of advanced economies (N = 33). (International Monetary Fund October 2009) This definition includes two special administrative regions (SARs) (Hong Kong SAR and Taiwan Province of China), and 31 countriesin North America, Europe, and Asia (see Table 1 for list of advanced economies).

Thirty-one of 33 (93.9 %) advanced economies responded to the survey; Israel and Singapore did not provide responses. The data were validated in 15 of 31 (48.4 %) advanced economies (Table 1). The age of adulthood for immunization purposes ranged from 15 (Spain) to 19 (Slovenia) years, with a median of 18 years. Twelve of 31 (38.7 %) advanced economies had a comprehensive adult vaccine schedule which describes the country or SAR’s adult vaccine recommendations in one document. The total number of vaccines or vaccine components recommended for adults ranged from one to 15 with a median of 10. Having a comprehensive adult vaccine schedule was associated with recommending more vaccines for adults [odds ratio (OR) = 1.38, 95 % confidence interval (CI): 1.007–1.891, p value 0.0452].

This survey is the first to describe the range of adult vaccine strategies, policies, and funding sources in 31 advanced economies. Roughly one-third of the advanced economies have a comprehensive adult immunization schedule that summarizes their recommendations. We found a correlation between having a comprehensive adult immunization schedule and recommending more vaccines for adults. Although the confidence interval was wide, this finding could indicate that the importance of adult vaccination and the perception of the severity of vaccine-preventable diseases may vary from place to place.

We found the most frequently recommended vaccines for adults are seasonal influenza, tetanus, diphtheria, pneumococcal, and hepatitis B. These data are not surprising given that these five vaccines have been widely used for more than 30 years and were more often initially recommended for adults rather than children compared with other vaccines, such as varicella or polio. (Hinman and Orenstein 2007; Michel and Lang 2011; Poland et al. 2010; Roush and Murphy 2007) The least frequently recommended adult vaccines are BCG, HPV, mumps, and herpes zoster. BCG vaccination has varying efficacy against tuberculosis, especially among adults (ACIP 1990), and HPV and herpes zoster are relatively new vaccines. We also found most adult vaccines are recommended for specific groups of adults rather than recommended to all adults, consistent with cost effectiveness and indications for most of these vaccines. The age threshold of adults defined by the surveyed countries ranged from 15 to 19 years, which may affect the comparability of the survey results.

Lowering the financial barriers to receiving vaccines increases vaccine uptake. (The Community Guide 2008) Therefore, an effective funding mechanism for adult vaccines is an important part of a comprehensive immunization strategy. Our results indicate increasing GDP per capita and increasing health expenditure per capita are associated with increased likelihood of a recommendation for a vaccine. We also found the majority of recommended adult vaccines are funded through public funds only. No international system of classifying health systems currently exists, and advanced economies may define public and private funding differently. The type of funding available may also be limited to public only if the advanced economy has a centrally run national health care system, such as the National Health Service in the UK.

Most recommended adult vaccines have a source of funding, whether it is public or private, but it is important to note that pneumococcal, polio, pertussis, varicella, mumps, and HPV vaccines do not have a funding mechanism in more than 25 % of recommending advanced economies. This lack of funding may be related to the length of time the vaccine has been recommended for adults, the epidemiology of disease burden, competing health interests, or the process of making vaccine recommendations in each advanced economy. In the survey, we asked for the year when a vaccine recommendation for adults was first made for each vaccine or component, but the majority of respondents did not provide a response. We did not have enough data to examine the relationship between funding mechanisms and health expenditure per capita. It may be that, as more government funds are spent on health in general, the need to fund adult vaccination is less perceived. However, this finding could be confounded by health care efficiency, as increased spending on health per capita does not necessarily correlate with improved quality of care. (Anderson and Frogner 2008) We did not ask about the processes of making vaccine recommendations in each advanced economy, which could be valuable in understanding the factors influencing adult vaccine policies. These could include deliberations by national or regional vaccine advisory committees, and how often vaccine policies are reviewed and updated. This information could be useful to understanding the decision-making process around vaccines and the relative importance of adult vaccination compared with other health priorities.

Vaccination coverage measurement is vital to evaluating immunization program progress. We found that, for all 16 vaccines or components except for seasonal influenza, the majority of recommending advanced economies do not have a coverage estimate available. The financial and structural resources needed for regular vaccination coverage measurement can be substantial, and adult vaccination may not be a health priority in many of these advanced economies.

We described vaccination coverage estimates for the three vaccines for which we have the most data: seasonal influenza, tetanus, and hepatitis B. Coverage rates vary substantially across similar age or risk groups. For seasonal influenza vaccine among adults 65 years and older, many advanced economies have reached coverage rates above 60 %, with a high of 82 % in the Netherlands. In comparison, a number of advanced economies have coverage below 40 % among the same age group. This may be related to the degree to which regular seasonal influenza vaccination is a long-standing part of preventive care.

We received responses from over 90 % of the invited respondents, and while the data are based on self-report, these were validated in roughly half of the respondents. Some respondents expressed confusion about the meaning of a vaccine “recommendation,” and we received some comments that a vaccine recommendation could be made by a range of groups, including the government or Ministry of Health and also by health care provider associations and vaccine manufacturers. Because this was a survey of adult vaccine policies, we asked about vaccines recommended by the government, Ministry of Health, or another official policy-making body in the advanced economy. We did not ask about the vaccine safety systems in these advanced economies, which is another important component of a vaccination program.

While ongoing vaccine uptake measurement can be resource intensive, guidelines to establishing such systems may be helpful for these advanced economies. A consensus statement issued by the European Union Geriatric Medicine Society and International Association of Gerontology and Geriatrics-European Union in 2009 advocated for strengthening and harmonizing vaccine strategies for adults 60 years and older at the European level. (Michel et al. 2009) Policies and programs are important not only for older adults, but for all adults to protect the well-being and health of the entire population. Advanced economies are experiencing aging of their populations, and with continuing improvements in medicine and the quality of life, public health will need to consider a shift in funding from childhood-based vaccination programs to “lifespan” programs. (Michel and Lang 2011; Poland et al. 2010).

The reduced effectiveness of some adult vaccines when compared with childhood vaccines may be a barrier to increased uptake. (Osterholm et al. 2012) As the number of available vaccines continues to increase, standards for vaccination strategies will ease the introduction of new vaccines into existing vaccination practices. An increasing role exists for non-traditional/non-medical home immunization providers, such as pharmacists and community vaccinators, and standards should include considerations for partnering with these health providers. (Postema and Breiman 2000).