The effect of social determinants on immunization programs

Abstract

Vaccine preventable diseases have been responsible for a significant portion of childhood mortality in low-income countries, and have been re-emerging in medium- and high-income countries. The effectiveness of routine childhood immunization programs relies on multiple factors. Social determinants have the potential to affect immunization programs around the world, with globalization and ease of communication facilitating their effect. Exploring the types of social determinants affecting immunization efforts in various countries is of great importance to the ability of nations to address them, prevent the spread of disease and lower mortality rates. The social determinants affecting vaccination programs can vary among countries of different income levels, with some social determinants overlapping among these country groups. In this article we explore the various social determinants affecting routine immunization programs in low-, middle- and high-income countries and possible interventions to address them.

Keywords: :

• Millennium Developmental Goal
• childhood mortality
• immunizations
• social determinants
• vaccines

Introduction

Multiple vaccines are currently available worldwide against infectious pathogens, with many of them designated for routine childhood immunizations. In this regard, more than 25 different vaccines are licensed in the US for the prevention of infectious diseases.¹ However, immunization programs around the world are often not fully utilized. The successful implementation of immunization programs depends on multiple factors.² Although biological, epidemiological, economic and logistical factors related to vaccinations often attract the most attention, social determinants can have a significant effect on immunization efforts around the world. A recent systematic review addressing the reasons for under- or non-vaccination of children from low- and middle-income countries suggested that social determinants may have a substantial impact on routine childhood vaccination.³ Some social determinants may be similar in countries with any income level while others may be unique to specific populations. Understanding the effect of social determinants on routine immunization programs in various countries is important for the development of modalities to address them with the purpose of optimizing vaccination coverage. In this review we aim to identify and explore the various social determinants affecting routine childhood immunization programs in countries of low-, middle- and high-income levels. Furthermore, we attempt to highlight possible solutions as they relate to the various social determinants.

Low-Income Countries

Overview

Low-income countries carry a high burden of vaccine-preventable diseases,⁴ a situation which is often exacerbated by inconsistent vaccine supply.⁵ While lack of funding and inadequate infrastructure can present a challenge for immunization programs in low-income countries,⁶ social determinants appear to play an important role even when vaccines and health care services are available. In this regard, one study demonstrated that the availability of healthcare and vaccination services within reachable distance did not necessarily lead to their consistent utilization by the population,⁷ suggesting that individual or population determinants play a role in the success of immunization programs. Some social determinants are unique to low-income countries, while others share similarities with those of high- and medium-income countries.

Household Living Conditions

Several studies found an association between living conditions and vaccination rates in low-income countries. In rapidly growing slum areas of low-income countries, access to health care services in general and immunizations in particular were found to be limited, contributing to a large burden of infectious diseases⁸ and spread of infections to other communities.⁸ A higher quality of roofing was found to be positively associated with overall vaccination rates in Delhi, India⁹ and with higher measles immunization rates in the Lasbella district in Pakistan.¹⁰ These observations suggest that families that possess better housing are more likely to have their children immunized.

Household income was shown to play a major role in access to care, as many indirect costs associated with immunizations, such as transportation to clinics, were more tolerable for households with higher incomes.¹¹ In this regard, a cross-sectional study conducted in Delhi, India, demonstrated that a secure and salaried job held by the head of household was associated with higher probability of children being immunized.⁹ These findings indicate that poor living conditions are associated not only with reduced immunization rates, but also with increased incidence of disease, which in turn raises the overall burden placed on an existing poor health care infrastructure.

Parental education

Parental education in general, and about vaccines in particular, was described in multiple studies to be associated with higher child immunization rates, suggesting that education of parents plays a significant role in this regard. In a cross-sectional survey conducted in Delhi, India, maternal education was found to play an important role in the use of health care services as well as full immunization of children.⁹ In another cross-sectional survey conducted in Pakistan, maternal education as well as parents being fully informed about vaccinations were associated with full immunization of their children.¹⁰ Furthermore, general health knowledge was improved among both men and women who have had access to higher education,¹² suggesting the key role education plays in healthy behaviors including childhood immunizations. Lack of education can potentially lead to misconceptions about vaccines. In this regard, a study conducted in Uganda found that reduced participation in National Immunization Day for polio was due, at least in part, to concerns that vaccines may cause malaria or contain contraceptives.¹³

Religious and minority groups

Religious and cultural factors have been shown to affect immunization rates among different populations in low-income countries. Differences in religious affiliation were found to be associated with differences in immunization rates in a study conducted in Nigeria, where immunization rate was 66% among Christians but only 32% among Muslims.¹⁴ In addition, increased childhood mortality and poorer health were seen among Muslims as compared with Christians in studies from the Middle East and Africa.^15,16 Lower immunization rates among certain religious groups could be due to several factors such as marginalization and alienation from the surrounding society,¹⁵ limited access to social programs,¹⁵ and respect for their religious leaders’ opinions. In this regard, certain religious leaders have cited vaccinations as a sin against God.¹⁷

Migration

Belonging to a community was shown to have a strong positive association with full immunization coverage.¹⁸ In this regard, war related migration was found to be associated with increased rates of childhood mortality in Angola.¹⁹ The same study also showed that decreased access to age-appropriate immunizations was one of the disadvantages of migrant families as compared with non-migrant families.¹⁹ The transient nature of the refugee population and the lack of full vaccination coverage may be further complicated by the use of multi-dose vaccines, as follow up visits for multiple doses at the same centers is often not possible.²⁰ Low immunization coverage among migrant groups can lead to disease outbreaks which affect both the immigrant population as well as the host country. In this regard, measles outbreaks were described in several studies conducted among displaced populations.²¹ Most of these outbreaks occurred in post-conflict circumstances, where immunization status, nutrition, living conditions and refugee movements contributed to the transmission, illness and death from the disease.²¹ The migration of children between Burkina Faso and Cote D’Ivoire was found to contribute to a measles outbreak in Burkina Faso which occurred despite supplementary measles vaccination given to children in Burkina Faso shortly before the outbreak.²²

Gender-based inequity

In many low-income countries women are dependent on men socially, economically and culturally, and are at disadvantage compared with women in high-income countries. This disadvantage may start at infancy and continue throughout life.²³ One of the manifestations of this disadvantage is lack of preventive healthcare, particularly vaccinations, for females.^24-26 According to health surveys conducted in India between 1992 and 2006, girls had significantly lower basic immunization coverage as compared with boys.²⁶

Women’s role and power

The role of women in societal advancement has been investigated by several studies.²⁷ In many households in Uganda, for example, although mothers are the primary caretakers of children, fathers often make decisions about participation in government programs and their objections have often been identified as one of the barriers to their children’s participation in vaccination programs.¹³ Two major factors appear to particularly affect the role of women in facilitating childhood vaccinations: education and social support. Although the education of both parents was found to be important for healthy behaviors,¹² maternal education in particular has been cited as a key element in parental adherence to vaccination programs.^9,10,28 In this regard, a study conducted in sub-Saharan Africa demonstrated that women’s literacy was positively associated with increased healthcare access and usage.²⁹ In Ethiopia, studies led to the recommendation to educate mothers on the importance of family planning, breast feeding, and immunization programs in efforts to reduce child morbidity and mortality.³⁰ Social support for women, especially for mothers of newborns, was also identified as an important element in shaping attitudes toward health and care of children.³¹ In marginalized, extremely poor and hard to reach areas, mobilization of social support networks, combined with education and communication, were found to be effective in overcoming gender barriers and resistance to vaccination programs.³²

War and civil unrest

War and civil unrest have a deleterious effect on the physical and mental health of individuals within a population, including the prevalence of vaccine preventable diseases and the success of vaccination programs. As an example, a high prevalence of Hepatitis B was found in populations of internally displaced persons due to war in countries such as Pakistan, especially in rural environments.³³ Pakistan, which introduced the Hepatitis B vaccine in 2006,³⁴ has had a substantial population of internally displaced individuals due to the recent war on terrorism. Such populations have multiple risk factors for Hepatitis B as well as other vaccine preventable diseases, and are in great need of effective vaccination programs. However, war and civil unrest have a negative impact on the infrastructure necessary to deliver effective health services, including clean water, sanitation and electric power supply to allow proper cold chain capacity.³⁵ Delivery of vaccinations to rural areas becomes particularly difficult when transportation systems are destroyed.³⁶ In addition to destruction of transportation systems as a result of war, destruction of communication systems such as radio and telephone networks impacts vaccination programs due to an inability to inform the population of National Immunization Days as well as vaccine and medical staff availability.³⁶ The consequences of war also present a challenge to vaccination program surveillance, as measuring vaccination coverage and other health related metrics becomes difficult in the face of communication and transportation systems malfunction.³⁷ Thus, in areas stricken by continual civil unrest and war, such as the Sudan, the scarce and unreliable relief efforts, including vaccination, contribute to high prevalence of disease.³⁸

Traditional healers

Traditional healers often serve as primary health care providers in developing countries and mothers use their services for pediatric care to various degrees. Traditional medicine may include herbal, spiritual or religious practices. A study done in Haiti found that the use of traditional healers by mothers was negatively associated with the vaccination rates of their children.³⁹ Furthermore, in a study done in Pakistan, the use of traditional healers was found to be a risk factor for under-5 mortality.⁴⁰

Urban vs. rural place of residence

The 2011 Millennium Developmental Goals Report describes a higher rate of mortality among children from rural households.⁴¹ It is thus important to explore whether there are differences in routine childhood vaccination rates between urban and rural communities in low-income countries.

A study conducted in Papua New Guinea demonstrated a significantly higher rates of 3-dose DPT immunization at 6 mo of age in urban as compared with rural communities.⁴² A study done in Kilifi district in Kenya found that children from the Kilifi township received pentavalent vaccine doses earlier than children from rural areas.⁴³ Another study done in Indonesia found significantly higher rates of first-dose measles vaccination in urban as compared with rural areas.⁴⁴

The differences in immunization coverage between urban and rural children were linked to parental education, wealth, and the presence of a skilled birth attendant.⁴⁴ Additionally, misconception or lack of knowledge, health services issues, challenges with regard to travel or transport and family-related logistical issues were reported more frequently by rural residents as compared with urban residents.⁴² However, urban communities are not always homogeneous with respect to immunization coverage.⁸ Poor urban residents can represent a large proportion of the population in low-income countries.⁸ They may also have high proportions of migrants or people belonging to different ethnic groups.⁸ Thus these populations may not enjoy the advantages of urban communities with respect to education, proximity to health care services and ease of communication.⁸

Program accessibility

Accessibility to immunization programs was shown to have an impact on their utilization by various populations. A study conducted in Yemen demonstrated that longer geographical distance and longer driving time were associated with lower childhood immunization rates.⁴⁵ A study conducted in a poor district in Kenya showed that immunization rate ratios of the pentavalent vaccine decreased with each kilometer of distance from vaccine clinics to homes.⁴⁶ In this regard, a study conducted in Burkina Faso demonstrated that mortality of children under five years of age increased by 50% when the walking distance to healthcare facilities was longer than four hours,⁴⁷ and a study conducted in Pakistan showed that proximity to government healthcare centers led to increase in children’s immunization coverage.¹⁰ Another study conducted among the Bedouin Arabs in southern Israel, many of whom have lived a nomadic lifestyle away from Maternal and Child Centers, and are thus similar to populations in low-income countries, demonstrated low infant immunization coverage prior to the establishment of a population-specific intervention program.⁴⁸

Financial factors

Morbidity and mortality from vaccine-preventable diseases occur primarily in poor countries. It has been estimated that out of the approximately 162 million Disability-Adjusted Life Years (DALYs) that have been lost around the world from vaccine-preventable diseases, over 90% occurred in low-income countries.⁴⁹ Additionally, it was estimated that 87% of the 2.5 million deaths of children under 5 y of age worldwide have occurred in poor areas of the world.⁴ The Millennium Developmental Goal No. 4 (MDG 4) calls for a two-thirds reduction in the mortality of children under the age of 5 by the year 2015.⁵⁰ In order to meet MDG No. 4 in the poorest 72 countries of the world, an estimated US$ 11–15 billion are needed.⁵¹ Thus country-level financial factors have a substantial effect on the ability to effectively immunize populations in low-income countries.

Historically, financial resources for vaccines in low-income countries have been limited and inconsistent.^52-54 However, in recent years substantial efforts have been made to close the vaccination gap between high- and low-income countries. In this regard, the GAVI Alliance, which was launched in 2000, has been instrumental in supporting immunization efforts in low-income nations and working toward closing the immunization gap between low- and high-income countries.⁵⁵ The GAVI Alliance is a public-private partnership that brings together the World Health Organization (WHO), UN agencies, the World Bank, donor and recipient countries, public health institutions, the Bill and Melinda Gates Foundation, pharmaceutical manufacturers, and other members of the financial and philanthropic community.⁵⁶ Its support has been available to countries with gross National Income per Capita of US$ 1,000 (and more recently of US$ 1500) or less.⁵⁷ The GAVI Alliance offers a new model in which eligible countries submit detailed proposals which are evaluated by a panel of experts.⁵⁷ Thus far, GAVI has been instrumental in the introduction of new vaccines, enhancing the use of existing vaccines and promoting reduction in vaccine prices.⁵⁸ Future evaluation of GAVI’s long-term efforts is required.

Governance

The role of country-level governance in the introduction of vaccines was recently investigated in the context of new vaccine introduction to poor African nations.⁵⁵ In that study, country-level governance was found to be essential for the early introduction of new vaccines.⁵⁵ Country-level governance affects societies in multiple ways and it is currently assessed yearly by the World Bank.⁵⁹ Each country’s performance is evaluated based on six governance components; these are: political stability, government effectiveness, rule of law, control of corruption, regulatory control and voice and accountability.⁵⁹ Poor African counties with higher governance scores were more likely to effect early introduction of at least one new vaccine⁵⁵ indicating the importance of governance in the implementation of vaccination programs. Superior country-level governance was formerly demonstrated to have a substantial impact on health-related investments in developing countries.⁶⁰ Country-level governance may also have an effect on the infrastructure required for the successful implementation of vaccine programs, such as the ability to reach distant locations, cold chain capacity, safe disposal of used syringes and needles, as well as adequate numbers of trained personnel.⁶¹ In fact, country-level governance was found to be a stronger predictor of the initial introduction of new vaccines to poor African nations than healthcare-related financial indicators.⁵⁵

High- and Middle-Income Countries

Overview

Although high and middle-income countries have different financial circumstances and fewer logistical issues as compared with low-income countries, social factors do affect vaccination efforts in these nations. In high- and medium-income countries, vaccine safety concerns, philosophical issues, lack of education, and religious beliefs play an important role in affecting immunization programs. In addition, alternative medicine and concerns regarding violations of civil liberties have played a role in shaping societal and parental views about vaccinations.⁶²

Safety concerns

Parental concerns about the safety of vaccines and the impact of side effects on their children have often been cited as a factor affecting immunization with one or more vaccines. A well-known example of such concern was demonstrated in the last decade with regard to the presumed association of the Measles-Mumps-Rubella (MMR) vaccine with autism. This concern originated with the publication of an article in a reputable medical journal suggesting that such association exists.⁶³ Several other studies also suggested a link between the MMR vaccine and autism^64,65 but no causation was demonstrated. Although multiple larger studies performed since did not support such an association, and the main article proposing an association between the MMR vaccine and autism has since been retracted,⁶⁶ the effects of the 12 y from publication to retraction still exist and there are still parents that believe that this vaccine carries high risk.⁶⁷ In fact, it has taken over a decade for public health advocates to achieve a reduction in negative vaccine perceptions,⁶⁷ an effort which required resources that were thought by some to have been better utilized for the development and delivery of alternate vaccines.⁶⁸

The number of vaccines given to children presents another significant concern for parents. The total number of inoculations given to an individual child can consist of up to 26 injections by the age of 2.⁶⁹ Even when several vaccines are combined into a single injection, parents have expressed concern regarding the ability of children’s immune system to handle multiple vaccines simultaneously without becoming ‘overloaded’ and experiencing adverse side effects.⁷⁰

Information, Misinformation and the Internet

Information and misinformation transmitted through the media in general and the Internet in particular⁶² compounds the problem of parental concern. This is particularly due to vast quantities of unfiltered sources of information which are difficult for laypersons to discern and refute.⁶² Increasing efforts toward education may not be sufficient to address this issue, primarily as trust in medical and other professional sources has been eroded among certain individuals and societal groups.⁶² In this regard, perception that the interest of pharmaceutical companies is primarily financial have contributed, at least in part, to the reduced trust in vaccines as necessary components of health care.⁶⁹ The website thinktwice.com,⁷¹ for example, notes “30 tactics used by the medical profession to hoodwink the public,” the website of the Center for Research and Globalization ‘globalresearch.ca’ questions the safety of vaccines in general and for infants and the elderly in particular,⁷² and the website childbirthsolutions.com explores “the contradictions between medical science and immunization policy.”⁷³ It is interesting to note that media reports about vaccines have penetrated even some secluded populations that are usually insulated from the direct influence of the media, such as Orthodox Jewish communities.⁷⁴

Religious, cultural and personal beliefs

Religion-based and cultural beliefs have been reported as barriers to vaccination programs in medium- and high income countries. An example of one religious belief impacting universal immunization programs consists of the notion that health is given to a person by God and God will determine health without the need for medication.⁷⁵ Another religious objection consists of the notion that some vaccine viruses are grown in aborted fetal tissue cell lines.⁶⁹

In Israel, two measles outbreaks occurred in 2003 and 2004 within the Ultra Orthodox Jewish community in Jerusalem. These densely populated highly religious communities have been closed to outside influences which are perceived as threatening to their religion. Effective outreach to these populations which required involvement of their religious leadership emphasized the need for cultural sensitivity when immunization programs are concerned.⁷⁶

The recently licensed Human Papilloma Virus (HPV) vaccine elicited objection among certain societal groups because of personal beliefs. In this regard, black and Asian mothers living in the UK expressed objection to the HPV vaccine due to the sexual transmission of the virus and their belief that vaccinations could encourage sexual activity among adolescents.⁷⁵

According to the Center for Disease Control and Prevention (CDC), 48 US states allow exemptions from vaccine requirements for religious reasons and 21 for personal beliefs.⁷⁷ One study found that children and adolescents receiving exemptions from vaccinations were 35 times more prone to contracting measles as compared with vaccinated individuals.⁷⁸

Immigration

Many immigrant groups are currently residing in middle- and high- income countries. Immigration into these countries has led to demographical changes in many of them.⁷⁹ These populations, if under-immunized upon immigration or thereafter, may contribute to outbreaks of vaccine preventable diseases in the host countries. In this regard, inadequate vaccination was among the most common health problems noted among African immigrants in Australia.⁸⁰ A study conducted in Catalonia found significantly lower prevalence of antibodies to the Rubella virus in immigrant pregnant women as compared with indigenous pregnant women.⁸¹ Children of foreign-born mothers living in the US were found less likely to complete the full vaccination series by 18 mo of age as compared with children of US-born mothers.⁸² Several reasons were found to be associated with lower immunization coverage among immigrants. A study conducted in Poland found that low immunization levels among refugees were due to the use of different health centers, postponement of vaccinations, and lack of health education among immigrant parents.⁸³ Language and cultural beliefs were described to impede many routine health care practices among Chinese immigrants in Montreal, Canada.⁷⁹ A study conducted among Hmong parents in California found that socioeconomic status and the utilization of traditional Hmong medicine constituted barriers to immunizations;⁸⁴ command of the English language, on the other hand was not perceived by these parents to affect vaccination program participation.⁸⁴ A study of Latino children in Colorado found that sending appointment reminder cards in Spanish helped improve immunization rates.⁸⁵

Urban Vs. rural place of residence

Differences in routine immunization patterns were reported in several high and medium income countries. A study conducted in Ireland found that lack of primary vaccination was associated with living in the rural area of the country, among other risk factors.⁸⁶ An HPV vaccine uptake study conducted in the US found lower uptake of free vaccines in rural college clinics as compared with urban college clinics.⁸⁷ Age-appropriate vaccination rates were also lower among rural children as compared with urban children in Nonsan City in South Korea.⁸⁸

Complementary and alternative medicine

Complementary and alternative medicine (CAM) have grown increasingly popular over the years,⁸⁹ They include naturopathic, homeopathic, chiropractic and anthroposophic medicine. Their popularity is due, at least in part, to the belief that conventional medicine, including vaccine administration, is associated with greater risk than benefit.⁸⁹ Thus, certain CAM practitioners advise patients against immunizations^89,90 and several studies demonstrated lower vaccination rates among CAM pediatric patients,^90-92 with higher rate of vaccine-preventable diseases.⁹² In addition to the belief that vaccines are associated with greater risk than harm, a strong philosophical reasoning plays a significant role in the choices made by certain CAM patients. Anthroposophy, for example, is a philosophical approach that is applied to several areas of life including medicine and education.⁹³ Antroposophical medicine used for pediatric care has been particularly popular in certain European countries.⁹³ Parents practicing anthroposophy believe in the mental and physical strengthening effects of natural infections like measles.⁹⁴ Several measles outbreaks originating in anthroposophic communities and schools in Europe,⁹³ highlight the role of these philosophical beliefs in immunization uptake.

Financial factors

Despite the relative wealth of high- and medium-income countries, financial factors do affect vaccinations in these countries.⁹⁵ In the US, disparities in income that have affected immunization rates led to the establishment of the Vaccines for Children program (VFC). This state-operated federal entitlement program provides funding for recommended vaccines to children from low socioeconomic status.^96,97 The program was established in 1994, following lessons learned from a measles outbreak lasting from 1989 to 1991. The length, prevalence and morbidity rate of that outbreak was related to low measles vaccination coverage among children of low socioeconomic status.^98,99

Eligibility for vaccination through the VFC program is restricted to children and adolescents under the age of 19 who are either uninsured, Medicaid-eligible, or are of American Indian or Alaskan Native heritage.¹⁰⁰ Additionally, children who have health insurance that fails to cover vaccination costs are eligible for the VFC program providing they are served by a federally-qualified health care center (FQHC) or rural health clinic (RHC).¹⁰⁰ In 2006, it was estimated that 50% of all children and adolescents in the US qualified for VFC funds.¹⁰⁰ Immunization monitoring data suggest that, on the whole, VFC has had a positive effect on vaccination coverage of its target population.^101,102 However, a recent study showed that delivery and administration of VFC-funded influenza vaccines were delayed by one month, as compared with privately purchased influenza vaccines.¹⁰³ This may have resulted in the lower rates of completion of the two doses required for children under 9 y of age who receive the influenza vaccine for the first time.¹⁰³

Newly recommended vaccines and combination vaccines have significantly increased the cost of vaccinations, and reimbursement by insurance companies in the US does not always fully cover their costs.¹⁰⁴ Current healthcare reform efforts may not have fully addressed this issue, which will probably require additional evaluation.⁹⁵

Ethical issues

The decision of parents in many developed countries not to immunize their children has created an ethical concern. Parents’ wish to protect their own children from potential harm is understandable. However, avoiding vaccination can lead to inadequate immunization rates followed by increased prevalence of vaccine-preventable diseases, resulting in significant and potentially tragic consequences to the societies in which these children live.¹⁰⁵ Parents’ perception of risk from a vaccine-preventable disease may be influenced by their circumstances.¹⁰⁵ In this regard, a disease that may seem trivial in developed countries with ample resources, can result in devastating outcome in developing countries where nutrition and access to health care are lacking.¹⁰⁵ Issues of benefits vs. harm, the child’s best interests, the benefits to the community as well as justice were suggested for consideration by both policy makers and children.¹⁰⁵ Mandatory immunization has been recommended and practiced by developed countries and is considered to be an effective public health practice.^106,107 However, some scholars have claimed that compulsory immunization can be challenging from a moral and ethical perspective.¹⁰⁶ They thus suggested that an effort should be made to raise immunization rates by other non-compulsory methods.¹⁰⁶

Discussion

Social determinants can affect routine childhood immunization efforts in low-, medium- and high-income populations. These can in turn affect herd immunity and the introduction of new vaccines, both of which are important for the reduction of childhood morbidity and mortality. For these reasons it is of outmost importance to gain full understanding of the impact of social determinants and address them as part of the overall task of overcoming barriers to immunizations.

Our review indicates that countries of various income levels share multiple similar social determinants that affect immunization. In addition, many of the social determinants reviewed here appear to be interconnected. For example, immunization program accessibility in low-income countries can result from physical distance which may be pertinent for people living in rural areas. In addition, people living in rural areas may have fewer educational opportunities which were shown to be important for childhood immunization program utilization. Interconnectivity between social determinants applies also to middle- and high- income countries. In this regard, the lower immunization rates found among certain immigrant groups can result from language barriers, cultural differences, educational differences as well as philosophical beliefs.

Recognizing the magnitude of the effect of social determinants on immunization programs is essential for designing appropriate and effective interventions. Such interventions are of particular importance for reducing inequalities in vaccinations among different countries and populations.

Various strategies have been suggested to address the different social determinants affecting immunizations. Many of them require collaborative efforts in order to be successful.⁸ A comprehensive assessment that includes specific disease epidemiology, target population characteristics, community needs, and existing health care issues is necessary prior to the introduction of programmatic changes that can be sustained over time.⁸ For example, an assessment of childhood immunizations among poor urban population in Mozambique identified that a large percentage of children were not immunized due to missed opportunities.⁸ Identification of these missed opportunities can lead to community-specific solutions to increase immunization rates.

Limited accessibility to healthcare facilities was addressed by several programs. In this regard, school and community based outreach programs have been suggested as one method to improve vaccine delivery.¹⁰⁸ A study in Saudi Arabia found that rural patients were highly satisfied with mobile clinics providing primary health care.¹⁰⁹

Maternal-Child Health centers were established for Bedouin Arabs who live a nomadic life style in Southern Israel. One of these centers and 2 mobile immunization teams were established on all-terrain vehicles to increase accessibility to remote desert areas.⁴⁸ One study found that home delivery of vaccines helped improve immunizations of children in rural Pakistan.¹¹⁰ Furthermore, contact with mothers after delivery by a professional of the same cultural background speaking the mother’s language helped to establish follow up well-baby care and immunizations.⁴⁸

Education of families about vaccines was shown to be associated with higher immunization coverage of children.¹⁰ Community-based, culturally sensitive educational programs where educators originated from among the target population were positively received by Bedouin Arab mothers in Southern Israel.⁴⁸ In this regard, increased cultural sensitivity including language appropriate interventions were helpful among immigrant populations in high-income countries.⁷⁹

Successful efforts to address the transportation and communication barriers to vaccinations which are associated with war have included the use of motorcycles and other appropriate vehicles to navigate difficult terrains.¹¹¹ Furthermore, telehealth and telemedicine systems have been used to assist with increased communication and education efforts in areas where health worker coverage is sparse.¹¹²

Outreach to religious leaders and religious or philosophy-based populations may be important when addressing religion- and belief-based issues.⁷⁸ Since religion- and belief-based refusal or reluctance toward vaccination has been reported worldwide, such outreach may be applicable in any income level country.^17,76,78 Similarly, reaching out and training of traditional healers in the implementation of primary care activities including immunizations was found to be successful in several low-income countries around the world.¹¹³

A careful consideration of parental concerns and appropriate education appears to be particularly important based on the studies cited above; however, these may not be sufficient when addressing the so called “anti-vaccination movement” and the effect of media and the internet.⁶² This is because such opposition to vaccination does not result from an informational gap but rather social as well as political factors.⁶² In this regard, analysis of anti-vaccination websites reveled several common themes: suspicion of scientific and medical experts supporting vaccination, promotion of parents’ responsibility and autonomy and belief in alternative health models.⁶² Although thus far no specific modalities have been proven to be effective, understanding and acknowledgment of ideologies that underlie the position of anti-vaccination groups appears important to initiate a dialog⁶² and hopefully the re-establishment of trust in the value of vaccination. Furthermore, the impact of belief based exemptions from vaccination need to be more thoroughly examined and addressed as they can affect herd immunity and lead to resurgence of vaccine preventable diseases in medium- and high-income countries.

As the number of vaccines against infectious diseases is projected to increase, consideration of the social determinants affecting routine childhood vaccination efforts in high-, middle- and low- income countries becomes unavoidable. With the target date of achieving MDG 4 rapidly approaching, this task appears particularly vital.

Abbreviations:
MDG	=	Millennium Developmental Goal

Acknowledgments

A. G-F is a recipient of a grant for innovation in infectious disease research from the Nan A. Lightstone Foundation.