Beginning with the campaign to eradicate smallpox in the 1960s, the United States has been interested in the eradication of vaccine-preventable diseases (VPDs) in children worldwide, as well as vaccine research and development. The success of the smallpox eradication campaign led to the establishment of the World Health Organization's Expanded Programme on Immunization in 1974. Since then, global vaccination campaigns have been broadened and garnered near universal international support. Today, the U.S. government is a leading donor to global vaccination campaigns ( Figure 3 ). In FY2019, Congress appropriated $290 million in foreign aid for the Global Alliance for Vaccines and Immunization (GAVI, now called GAVI, the Vaccine Alliance) and $226 million for Department of Health and Human Services (HHS) to support child vaccine campaigns abroad. The authorization, appropriation, and oversight of U.S. funding for global child vaccination is thus an ongoing area of concern for many in Congress, as is the extent of donor coordination and burden-sharing for such efforts. Additional potential issues include the extent to which global child vaccination promotes U.S. foreign policy, development, and domestic health security (i.e., pandemic preparedness) goals. Donor-backed child vaccination campaigns have reduced mortality in poor countries, though occasionally they have faced setbacks. In the early 1990s, U.S. foreign assistance for large-scale vaccination campaigns led by the World Health Organization (WHO) and the United Nations Children's Fund (UNICEF), and with significant U.S. funding and technical support, contributed to an approximately 80% immunization rate for three doses of the diphtheria, tetanus, and pertussis vaccine (DTP3). Progress, as measured by vaccination rates, stalled on certain vaccinesânotably the diphtheria, tetanus, pertussis, and measles vaccinesâin the late-1990s for a variety of reasons, including management of vaccine stocks, effective vaccine delivery, and cost of vaccinations. In 2000, a public-private partnership, the Global Alliance for Vaccines and Immunization (GAVI) was launched to address both declining global momentum for child immunization campaigns and declining funding for these programs. Since its inception, GAVI has supported the immunization of 700 million children. As a founding member of GAVI, the United States holds a rotating seat on GAVI's board and provides it with funding (see " U.S. Role and Funding "). Vaccinations are considered one of the most cost-effective ways to prevent infectious disease and associated morbidity and mortality. WHO recommends that all children receive 10 vaccines ( Table 1 ). Receiving the recommended childhood vaccinations can protect the recipient from illness and death associated with VPDs, and can reduce infectious disease spread. According to UNICEF, these immunizations save around 3 million lives per year. Globally, coverage of recommended childhood vaccines vary, with VPDs causing high levels of morbidity (illness) and mortality (death), primarily in certain low- and middle-income countries that have had limited success in achieving universal coverage. Recently, some high-income countries, for example France and the United States, have seen exponential increases in cases of VPDs, due primarily to vaccine hesitancy. According to GAVI, from 2000 through 2018, more than 760 million children worldwide were immunized against VPDs, including 66 million children in 2018. Approximately 100 million children are immunized each year. At the end of 2018, 20 million infants and children worldwide had not received the full schedule of recommended vaccines. According to GAVI, full vaccination coverage could prevent one in seven deaths in under-5 children. Over 1.5 million children die every year from VPDs. Nearly 60% of these children live in 10 countries: Angola, Brazil, DRC, Ethiopia, India, Indonesia, Nigeria, Pakistan, the Philippines, and Vietnam. From 1990 to 2017, overall child deaths fell from 12.7 million to 5.8 million, largely due to gains made by global immunization campaigns and expanded national immunization programs. For example, from 2000 to 2017, scaled-up measles vaccination coverage averted an estimated 15.6 million deaths from the disease. Global coverage for several recommended vaccines has continued to climb over the past decade (see Figure 1 ); however, progress in expanding the number of children vaccinated with DTP3 (a three-dose diphtheria, tetanus and pertussis vaccine) has stagnated in recent years, though its coverage remains higher than coverage for other required vaccinations (see Figure 2 ). GAVI reports recent stagnation in coverage is due to "acute problems that a small number of previously high performing countries have faced." Diphtheria, tetanus and pertussis are particularly fatal to neonates, new mothers, and pregnant women. Maternal and neonatal tetanus (MNTE) has been almost eliminated globally, and since 2000 there has been an 85% reduction in newborn deaths from tetanus. As of March 2019, MNTE remains present in 14 countries. In 2018, 86% of children under the age of one received all three doses of the DTP3 vaccine. As global uptake of childhood vaccines improves, an increasing proportion of child deaths are concentrated in sub-Saharan Africa and Southern Asia: four out of every five under-5 child deaths occur in these regions. Figure 2 displays geographical immunization coverage for three doses of the DTP3 vaccine. DTP3 immunization coverage is used as a proxy indicator to estimate the proportion of children vaccinated within their first year of life. In 2015, U.N. member states adopted the Sustainable Development Goals (SDG) as a common agenda to help alleviate global poverty, improve health and education, reduce inequality, and spur economic growth by 2030. SDG Goal 3 is to end preventable deaths of newborns and under-5 children by 2030, with a targeted reduction of under-5 mortality to 25 per 1,000 live births in every country. (According to 2018 figures, 80 countries worldwide have under-5 mortality rates that are higher than 25 per 1,000 live births.) International efforts to decrease vaccine-preventable deaths among children younger than five years are led by international organizations such as WHO, UNICEF, and GAVI, with significant U.S. support (detailed in the section on U.S. role and funding). Several multilateral initiatives and commitments frame these efforts. UNICEF. UNICEF supports immunization programs globally and is the biggest single global purchaser of vaccines. The organization focuses on providing vaccinations, monitoring and improving vaccine supply and quality (e.g., ensuring that vaccines are consistently stored at an appropriate temperature, known as "the cold chain"), vaccine innovation (e.g., research and development), and disease eradication and elimination programs. UNICEF has a permanent seat on GAVI's board and procures all vaccines for GAVI-supported programs to ensure a reliable supply of high-quality and affordable vaccines. UNICEF's immunization goals align with WHO targets outlined in the Global Vaccine Action Plan (GVAP) 2011-2020; to reach 90% of children under the age of one with routine immunization, and achieve 80% immunization coverage for every country district by 2020. WHO . The WHO launched its first 10-year strategic framework on vaccines in 2005. The Global Immunization Vision and Strategy Immunization was intended to extend immunization achievements and to continue encouraging governments to maintain a commitment to protect their populations from VPDs. The GVAP for 2011-2020 was released in 2010 to build on the 2005 strategic framework. The GVAP aligns with the WHO's 2015-2030 strategic goals, which include promoting the development of new vaccines and vaccine delivery technologies to meet public health priorities, establishing norms and standards for vaccines and vaccine delivery technology, and ensuring quality. The WHO also develops evidence-based immunization policy recommendations for member states through an independent advisory group, the Strategic Advisory Group of Experts on Immunization (SAGE). SAGE meets biannually to develop recommendations based on available evidence on immunization and vaccines. It also convenes on an emergency basis to discuss disease outbreaks and vaccine-related concerns (e.g., experimental Ebola vaccines). GAVI , the Vaccine Alliance. GAVI is a multilaterally funded public-private partnership. It was founded in 2000 by the United States, the WHO, the United Nations, the World Bank, and the Bill and Melinda Gates Foundation to expand global access to vaccines and prevent deaths from VPDs. GAVI is guided by five year strategic plans, the Phase IV strategy for 2015-2020 aligns with the goals outlined in the GVAP. In 2019, GAVI set the overall goal to immunize 300 million children by 2025, and save 5-6 million lives in the long term. For more information on GAVI, see the section under U.S. Funding for Multilateral Initiatives. Various factors affect global immunization coverage, including vaccine hesitancy and stigma, geographic location, inadequate country capacity, and poverty and socioeconomic status. Vaccine hesitancy and stigma. Recently, a resurgence of certain VPDs has caused concern among public health officials and drawn attention to the challenges of vaccine hesitancy and stigma. For example, polio continues to elude global eradication, and in 2019 some middle- and high-income countries experienced a resurgence of measles, due to a variety of factors, including reluctance among some individuals and religious communities to vaccinate their children. In April 2019, the WHO reported a 300% increase in global measles cases compared to the same period in 2018, with the greatest surges in cases in the Americas, the Middle East, and Europe. Prompted in part by this resurgence, the WHO listed "vaccine hesitancy" as one of the 10 biggest global public health threats. Corruption, authoritarian governance, and social or political discrimination can fuel vaccine hesitancy by undermining citizens' trust in authority figures (including government officials and health workers involved in vaccine campaigns). For example, Nigeria was close to eliminating polio for many years but did not do so until recently. Vaccination campaign efforts were hampered in part by conspiracy theories, "vaccine stigma," as well as by ethical concerns about government regulations and pharmaceutical industry practices. Vaccine stigma, for its part, arises when a community normalizes vaccine denial. Geographic location . Geographical distance from health centers negatively impacts vaccination coverage. Underserved populations within any given country often shoulder a heavier burden of disease, and they may lack access to basic medical care. Notably, vaccine coverage disparities between children in urban and rural areas persist throughout the world, and commonly exacerbate disease spread within a certain geographical area. For example, according to the WHO, in some countries (e.g., Nigeria and Indonesia), coverage of the measles vaccine in rural areas is 33% lower than in urban areas. Poverty, s ocioeconomic status , and social determinants of health. Vaccination coverage in low-income countries (41%) lags behind coverage in high-income countries (90%). Medical systems in many low-income countries are often underfunded and unable to vaccinate enough children to stop a virus's spread even with donor aid. In addition, researchers have found that inequities in vaccination coverage are associated with individual socioeconomic determinants, such as a family's income level and the educational status of a child's mother. Children born into poverty are almost twice as likely to die before the age of five as those from wealthier families, and researchers suggest that unequal access to vaccines is a key factor. Vaccine coverage for the richest fifth of the population in some countries is up to 58% higher than for the poorest fifth. Fragile and conflict settings . UNICEF reports that 40% of unvaccinated children live in countries affected by armed conflict or other humanitarian challenges. Often, already fragile health care infrastructure is further crippled by armed conflict, which can hinder health workers in carrying out vaccinations and interfere with proper disease treatment and containment. Humanitarian settings such as refugee and internal displacement camps can also foster conditions (e.g., poor nutrition, overcrowding, and unsanitary conditions) conducive to the rapid spread of infectious diseases. According to UNICEF estimates, as of 2015, half of the 10 countries that had under 50% diphtheria, tetanus, and pertussis vaccine coverageâthe Central African Republic, Somalia, South Sudan, Syria, and Ukraineâhad experienced conflicts or other humanitarian emergencies. Other conflict-affected countries have seen spikes in VPD cases, such as a 2019 surge in measles cases in the Democratic Republic of Congo (DRC), which has killed more people than the ongoing Ebola outbreak in that country. Congress has historically supported global child vaccination programs, both as a component of U.S. foreign assistance and as part of efforts to eradicate infectious diseases that might affect Americans at home or abroad. Through annual appropriations for the Department of Health and Human Services and the Department of State and Foreign Operations (SFOPS), Congress funds global immunization activities through the Centers for Disease Control (CDC), the United States Agency for International Development (USAID), and the Global Alliance for Vaccines and Immunization (GAVI, now called GAVI, the Vaccine Alliance). The U.S. Agency for International Development (USAID) and the Centers for Disease Control and Prevention (CDC) are the primary U.S. federal agencies involved in international vaccination provision and immunization campaigns. These campaigns support the 2016-2020 Strategic Framework for Global Immunization and the WHO's 2011-2020 Global Vaccine Action Plan , the agencies work with country governments to strengthen immunization programs by bolstering infectious disease surveillance, increasing laboratory capacity, and strengthening public health workforce capacity. The efforts of both agencies align with the 2010 HHS National Vaccine Plan, the Global Health Security Agenda, and the U.N.'s 2030 Sustainable Development Goals. CDC and USAID also support routine immunizations worldwide through enhanced supply chain management and product procurement assistance. Related efforts are implemented bilaterally and through international partnerships with the WHO, UNICEF, the World Bank, and others. In addition, CDC, along with the Department of Defense, finances the research and development of new vaccines. The CDC has played a central role in controlling vaccine-preventable diseases since it established the CDC Smallpox Eradication Program in January 1966. The Global Immunization Division of the CDC's Center for Global Health is responsible for coordinating CDC's global immunization activities. To support these activities, the CDC provides scientific and public health expertise in infectious disease epidemiology and surveillance by building laboratory capacity and helping to implement evidence-based prevention strategies. CDC also carries out clinical trials and epidemiologic studies. Funding for the CDC's Global Immunization Program is detailed in Table 2 . The majority of CDC's efforts are focused on polio, with smaller funding allocations for measles and other VPDs. Global vaccination campaigns against polio have lowered the worldwide incidence of polio by 99% compared with that of 1988, and in 2018 only two countries recorded wild polio cases: Afghanistan and Pakistan. Vaccine-derived poliovirus continues to be detected in Nigeria, but as of August 21, 2019, no cases had been confirmed there in three years. The CDC's programming is based on its 2016-2020 Strategic Framework for Global Immunization , which builds on three previous strategic frameworks and outlines five goals: 1. Control, eliminate, or eradicate vaccine-preventable diseases to reduce death and disability globally. 2. Strengthen country ownership, policy and practices, and partnerships. 3. Ensure quality of vaccination delivery to achieve high and equitable coverage. 4. Strengthen surveillance and immunization information to prevent, detect, and respond to vaccine-preventable diseases. 5. Conduct and promote research, innovation, and evaluation. To implement the strategic framework, the CDC works with USAID, UNICEF, GAVI, and other stakeholders. The strategy is aligned with the HHS National Vaccine Plan 2010, the Global Health Security Agenda, and the WHO Global Vaccine Action Plan 2011-2020. In FY2019, Congress appropriated more funding for CDC global immunization programs than the Trump Administration sought and more than was appropriated in prior years ( Table 2 ). The Administration's FY2019 and FY2020 budget requests would have reduced funding for global immunization activities and proposed that the CDC "focus its global immunization activities to continue progress towards polio eradication, as well as measles and rubella elimination in countries with the highest disease burden." To strengthen routine immunization campaigns and community-based disease surveillance, USAID works with foreign countries' ministries of health and provides funding to GAVI. These actions are part of the agency's strategy to prevent child and maternal deaths, which it also supports through capacity building for foreign health systems. For example, in Ethiopia, the agency works with Ethiopia's Ministry of Health to train community volunteers to identify symptoms of vaccine-preventable diseases (e.g., paralysis due to polio) and track "vaccine defaulters" (individuals who do not receive the full schedule of immunizations) to keep them on schedule. The United States, through contributions to international organizations and GAVI, provides significant support for multilateral immunization and vaccination programs ( Figure 3 ). Such support is intended to complement U.S. bilateral efforts in this arena while enabling the United States to expand its reach and provide opportunities for collaboration and burden sharing. GAVI is a multilaterally funded public-private partnership. It was founded in 2000 by the United States, the WHO, the United Nations, the World Bank, and the Bill and Melinda Gates Foundation to expand global access to vaccines and prevent deaths from VPDs. The United States played a central role in the creation of GAVI and continues to be involved in GAVI's governance, strategic planning, and funding. U.S. support of GAVI is intended to accelerate access to vaccines, strengthen vaccine delivery platforms, and work with country governments to sustain immunization programs. The United States is GAVI's third largest donor, having provided nearly $2 billion of the $21 billion donated to GAVI since its founding ( Figure 3 ). Congress appropriates U.S. funding for GAVI via USAID's Global Health Programs (GHP) account in annual SFOPS appropriations measures. In turn, the United States holds a seat on GAVI's board, as do the WHO and UNICEF, which also receive U.S. funding ( Figure 4 ). Table 3 details U.S. budget requests and enacted appropriations for GAVI from FY2015 to FY2020. During the Obama Administration, congressional appropriators met the Administration's requests to increase funding for GAVI year on year. In line with the Trump Administration's broad calls for cuts to foreign assistance, the Administration proposed $250 million for GAVI in FY2019 and in FY2020, a $40 million decrease from the FY2018-enacted level. In FY2019, Congress appropriated $290 million for GAVI, the same level as in FY2018. Congress has continued to demonstrate interest in supporting child vaccinations for VPDs overseasâfor example, by appropriating increasing levels of funding for related programs. However, numerous global outbreaks of VPDs have raised concerns about whether the progress made in preventing and eradicating communicable diseases can be maintained. In light of recent events, and in the context of the FY2020 appropriations process (and beyond), Congress may examine a few additional issues. One area that could be explored is the effectiveness of global vaccination campaigns as a tool of domestic pandemic preparedness. U.S. government public health officials have argued that the global resurgence of certain vaccine-preventable diseases, particularly measles and mumps, may threaten U.S. public health. Recent outbreaks of vaccine-preventable diseases in the United States have been traced to travelers from Europe and abroad, and the CDC reports that these travelers, coupled with domestic vaccine hesitancy, are the main cause of outbreaks in the United States. In March 2019, the full Senate Committee on Health, Education, Labor and Pensions (HELP) held a hearing to discuss the reasons behind preventable disease outbreaks, including imported cases of vaccine-preventable diseases linked to international travelers. As these outbreaks continue, Congress may continue to consider its oversight of, and federal government involvement in, issues surrounding vaccines, such as misinformation campaigns and their role in vaccine hesitancy. Another core area of interest relates to U.S. funding, foreign policy objectives, and foreign aid programs supporting immunization. The U.S. government has long-included vaccination as a core component of foreign policy, and as a foreign aid priority. Recently, the Trump Administration requested cuts to global health funding, including for U.S. agencies involved in global vaccination campaigns. The Administration contends that the funding requests will not affect programs and that "the reduction reflects the Administration's intent to further focus funds on countries, populations, and programs where resources will have the greatest public health impact ... [and] CDC will focus its global immunization activities to continue progress towards polio eradication, as well as measles and rubella elimination in the countries with the highest disease burden." Some experts argue that stagnation in vaccination coverage and the resurgence of some vaccine-preventable diseases are "alarm bells," and have expressed concern about flat support for global vaccine campaigns leading to a continued resurgence of vaccine-preventable diseases. These issues raise questions about burden sharing and the role of other high-income country donors in global immunization funding, as well as factors affecting the efficacy of global campaigns to increase vaccination rates. 
For more than 50 years, the United States has taken an interest in the eradication of vaccine-preventable diseases (VPDs) in children worldwide, as well as vaccine research and development, particularly since playing a vital role in the global campaign to eradicate smallpox in the 1960s. Since then, vaccinating children against VPDs has been a major U.S. foreign policy effort. Vaccinations are one of the most cost-effective ways to prevent infectious disease and associated morbidity and mortality. According to UNICEF, immunizations save around 3 million lives per year. As of 2019, VPDs continue to cause high levels of morbidity (illness) and mortality (death), and the World Health Organization (WHO) notes that the adoption of new vaccines by low- and middle-income countries (which often have the highest disease burdens) has been slower than in high-income countries. Receiving a vaccination during childhood can protect the recipient from VPDs, decrease the spread of related diseases, and improve child survival prospects (as children, particularly those under five years old, are more likely than adults to die from VPDs). Recently, a global resurgence of certain VPDs has caused concern among public health officials and drawn attention to the challenges of vaccine hesitancy and stigma. For example, polio continues to elude global eradication and remains endemic in three countries. In 2019 measles has seen a resurgence in some middle- and high-income countries due to a variety of factors, including reluctance among some individuals and religious communities to vaccinate their children. In April 2019, the WHO reported a n increase in global measles cases compared to the same period in 2018, with the greatest surges in cases in the Americas, the Middle East, and Europe. A number of European countries are at risk of or have lost their measles eradication certificate from the WHO, raising questions about global consensus on the use of vaccines, participation in and support for the Global Alliance for Vaccines and Immunization (GAVI, now called GAVI, the Vaccine Alliance) and other global immunization efforts. Prompted in part by this global resurgence, the WHO has listed "vaccine hesitancy" as one of the 10 biggest global public health threats. The U.S. government is the second-leading government donor to global vaccination campaigns. Through annual appropriations to the Department of Health and Human Services (HHS) and the Department of State, Congress funds global immunization activities through the Centers for Disease Control and Prevention (CDC), the United States Agency for International Development (USAID), and GAVI. In recent years, annual appropriations by Congress for multilateral immunizations campaigns led by GAVI have averaged $290 million and $226 million for bilateral campaigns led by CDC. USAID works to support routine immunization overseas through health systems strengthening, and Global Polio Eradication Initiative Activities. The authorization, appropriation, and oversight of U.S. funding for global child vaccination is thus an ongoing area of concern for many in Congress. Other key issues for Congress include the extent of donor coordination and burden-sharing for such efforts, and the extent to which global child vaccination promotes U.S. foreign policy, development, and domestic health security (i.e., pandemic preparedness) goals.