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
We have demonstrated policies recommending vaccination for adults, funding mechanisms for adult vaccine administration, and routine adult vaccination coverage assessment vary and are often lacking in the countries with advanced economies surveyed. Newer vaccines are less likely to be recommended for adults than older ones. Funding of adult vaccination is associated with recommendations for adult vaccine use. Most recommended adult vaccines are funded with public funds alone. These elements of stable funding, standard recommendations, and routine vaccine coverage assessment are essential components of successful childhood immunization programs. For adult vaccination to be as effective as childhood programs, countries should strive to include them for their adult populations.