Estimating the costs of achieving the WHO–UNICEF Global Immunization Vision and Strategy, 2006–2015
Lara J Wolfson a, François Gasse b, Shook-Pui Lee-Martin c, Patrick Lydon d, Ahmed Magan b, Abdelmajid Tibouti b, Benjamin Johns e, Raymond Hutubessy a, Peter Salama b, Jean-Marie Okwo-Bele d
In 2005, the World Health Assembly approved, and the United Nations Children’s Fund (UNICEF) Executive Board endorsed, the Global Immunization Vision and Strategy (GIVS).1,2 The primary objective of GIVS is to reduce vaccine-preventable disease mortality and morbidity by two-thirds by 2015 compared to 2000, a contribution towards achieving the Millennium Development Goals, especially Goal 4, which calls for a two-thirds reduction of under-5 mortality by 2015.3
GIVS identifies four strategic areas: immunizing more people against more diseases; introducing newly available vaccines and technologies; linking immunization to other critical health interventions; and managing vaccination programmes and activities within the context of global interdependence. GIVS articulates more than 25 new ideas and innovative approaches, and it is anticipated that countries will adopt the strategies most suited to their needs.
GIVS was developed in the context of increasing resources for immunization; in 1999 a public–private partnership, The Global Alliance for Vaccines and Immunization (GAVI Alliance) was initiated to provide financial support for immunization in the world’s poorest countries.4–6 By the end of 2005, government and private sources had pledged a total of US$ 3.3 billion to the GAVI Alliance, enabling it to provide support to 73 of 75 eligible countries. Between 2000 and 2005, total GAVI Alliance disbursements were US$ 760.5 million.7 GAVI Alliance’s resource outlook over the next decade has improved with the launch of two innovative funding mechanisms: the International Finance Facility for Immunisation (IFFIm),8 which could provide up to US$ 4 billion over the next 10 years, and the Pneumo Advance Market Commitment (AMC),9 which will provide US$ 1.5 billion to support low-income countries for the purchase of new vaccines against Streptococcus pneumoniae, a leading cause of childhood meningitis and pneumonia mortality.
In 2005, WHO and UNICEF undertook, as a companion to the GIVS document, to estimate the costs to reach immunization goals;10 this paper reports on the methods and results of that initial exercise.
Estimates were done for all low- and lower-middle-income countries (as of 2003)11 focusing on the subset of GAVI Alliance-eligible countries12 (for 2005–2010, countries with 2003 gross national income (GNI) per capita < US$ 1000), whose characteristics11,13,34 are highlighted in Table 1.
Cost components included
The costing has two main components: the first estimates current spending for immunization as of 2005 and how much will be needed to maintain the current immunization system. The second component estimates the incremental costs needed to scale up immunization coverage, including routine delivery and campaigns, and to introduce all available and safe vaccines according to WHO recommendations, including a finite set of new vaccines expected to become widely available (see Fig. 1).
Block A: maintenance of current routine system (baseline cost)
Current levels of investment in immunization were estimated using available data from 40 Financial Sustainability Plans (Block A1), and extrapolated for the period 2006–2015 by accounting for the impact of inflation and population increases (Block A3). They assume no change in vaccination schedules and no improvement in immunization coverage levels (Block A2). This does not include campaigns or vaccine costs.
Block B: vaccine costs
Vaccine costs were estimated by using coverage targets, population projections and applying the most recent available data on unit prices of different vaccine presentations. The estimates account for wastage rates and the need for buffer stock. The cost of safe injection equipment is bundled in the vaccine cost estimates. The element “below the line” represents the vaccine costs to continue immunization at 2005 levels, and “above the line” is the vaccine portion of scaling-up.
Block C: scaling-up of routine system
This is estimated using an ingredients-based approach. See Table 3.
Block D: campaigns
A schedule of needed campaigns was generated based on a combination of the projections of vaccine coverage and the required epidemiological coverage required to rapidly reduce the burden of disease. Campaign costs include both operational costs and vaccine costs.
For vaccine-specific costs, we define “traditional” vaccines as those in widespread use in the Expanded Programme on Immunization (EPI): Baccillus Calmette–Guérin (BCG), three doses each of diphtheria-tetanus-pertussis (DTP) and oral polio vaccine (OPV); (we assume use of this ceases in 2010 following polio eradication), a single dose of measles vaccine (MCV1) for children under one year of age, and two doses of tetanus toxoid (TT2+) vaccine for pregnant women. “Underused” vaccines include a second dose of measles (MCV2); three doses of hepatitis B (HepB) and Haemophilus influenzae type b (Hib) vaccines; yellow fever (YF); and rubella. “New” vaccines include three doses of rotavirus and conjugate pneumococcal vaccines; and single doses of Japanese encephalitis (JE) and conjugate meningococcal A (MenA) vaccine, for populations at risk.
Deriving country-specific projections
Costs are projected using the following assumptions: (a) routine coverage of existing vaccines based on actual 2005 country-specific immunization schedules in use reaching 90% by 2015; (b) mortality reduction campaigns; and (c) introduction of underused and new vaccines as rapidly as feasible. We developed a Microsoft Excel-based framework to generate country-specific coverage estimates and projections, the WHO Immunization Coverage Estimates and Trajectories (WHO ICE-T)14 (Annex 1, available at: http://www.who.int/immunization_financing/analyses/givs_costing_annex1.pdf).
Four types of vaccination campaigns are included: for rapid mortality reduction (tetanus, measles); and in conjunction with the introduction of new or underused vaccines (yellow fever and meningococcal A). The schedule of campaigns occur in each country based on expected coverage levels, the joint UNICEF and WHO strategic plans for Measles Mortality Reduction15 and Maternal and Neonatal Tetanus elimination,16,17 and the assumed year of introduction of new or underused vaccines. If the expected routine coverage levels are achieved by 2015, we assume no further immunization campaigns are needed, except occasionally in isolated areas with very low routine coverage.
We assume measles campaigns are needed until adequate routine two-dose coverage is reached; and schedule the occurrence of such campaigns every three years when routine first-dose coverage is under 75% and then every four years until first-dose routine coverage reaches 95% and routine second dose coverage reaches 90%. We assume that measles second-dose routine is introduced when a country reaches 80% routine first-dose coverage, and rubella vaccine is introduced after the first campaign following the introduction of routine second dose. Including a second dose of measles vaccine to the routine schedule adds a new visit to the schedule, another opportunity for children to contact the health-care system and receive other complementary interventions. Because of the complexity of adding a new visit to the schedule, we (conservatively) assume a five-year roll out to introduce a second dose.
For the introduction of underused (where not already used) and new vaccines, we assume phase-in over several years, based on grouping of countries by current immunization coverage and economic status (Annex 1, available at: http://www.who.int/immunization_financing/analyses/givs_costing_annex1.pdf). The dates of introduction of the pneumococcal, rotavirus, Hib, and HepB vaccines are country-specific, based on expert opinion, and it was assumed that in countries at risk, the YF vaccine would be introduced in 2006–2007, and that introduction of the meningococcal and JE vaccines would begin in 2009 and 2008 respectively.
Estimating country-specific costs
Estimating baseline costs (costing block A)
We developed an econometric model based on country-level data from the GAVI Alliance Financial Sustainability Planning (FSP)18,19 process to estimate current investments in immunization and how much will be needed to maintain immunization systems at the status quo, assuming no change in vaccination schedules and constant immunization coverage levels.
These baseline data from 40 countries (country groupings and characteristics are listed in Table 1), use a common methodology comparable across the subset of countries and are relatively recent (2002–2004). However, they are biased towards low-income countries (82%) because of GAVI Alliance-eligibility requirements and because the African Region is over-represented (57%).
All routine immunization-specific costs (see costing block C for a description of what is included in these costs), excluding spending on vaccines and campaigns, which we estimate separately in costing blocks B and D respectively, are included.20 To these were added shared health systems costs (mainly personnel and transportation costs). Inflationary adjustments21 are made to bring all costs to year 2000 US dollars for analysis, although all cost results are reported in 2005 dollars.
Various regressions using different linear combinations of Box-Cox22,23 transformed variables were tested, with size-effect variables (either population or surviving infants), coverage,34 rural population,24 a dummy variable indicating the use of the hepatitis B vaccine, and GNI per capita representing the independent variables significantly correlated with costs. Standard model selection techniques of backward and forwards stepwise selection were used to find the optimal combinations of variables to include in the regression model.25 We used nonparametric graphical modelling techniques26,27 to find the optimal transformations of both independent and dependent variables, and the “leaps and bounds” regression technique28 to determine which effects should be included in the model built from the transformed variables. Of over 270 models considered, the final model which simultaneously yielded good explanatory power (R² = 81%), had no violation of regression assumptions and had relative parsimony, and did not appear to systematically underestimate the total costs across the 40 data points used in estimating the model. Further details on this model can be found in Annex 2 (available at: http://www.who.int/immunization_financing/analyses/givs_costing_annex1.pdf).
The fitted regression equation is used to estimate total non-vaccine costs (inflation adjusted) for the 72 poorest countries for the years 2000–2015. We applied the same model to estimate the costs in the 45 lower-middle-income countries (see Table 1), acknowledging the limitation that this is extrapolating outside the support of the fitted regression.
Uncertainty bounds are based on applying standard formulae29 for predicting new observations from a fitted regression equation. The relative width of the uncertainty intervals for the baseline costing estimates was applied to estimates from other cost categories (B, C and D) to obtain overall uncertainty bounds.
Vaccine costs (costing block B)
We estimate the costs of traditional, underused and new vaccines for both campaign and routine use. For traditional and underused vaccines, UNICEF cost sheets, adjusted for inflation, provide price estimates, although this may be an underestimate of price for countries that are not using UNICEF or pooled procurement mechanisms.30 For new vaccines, prices are based on assumptions derived from available data and expert opinion, together with an assumption that prices will drop towards a “mature” price as demand rises. Vaccines are estimated as “bundled” costs, including safe injection supplies (syringes and safety boxes), and adjusted for wastage (based on vial sizes) and buffer stocks needed. Shipping and freight are also included as a percentage of the price per dose. Table 2 gives the assumed prices and assumptions used for wastage and freight charges applied to all countries. Costs for disposable items (e.g. syringes, safety boxes) are based on 2005 international prices and adjusted for inflation (3%) assuming wastage of 10% of the auto-disposable syringes (US$ 0.074), reconstitution syringes (US$ 0.03) and safety boxes (100-syringe capacity, US$ 0.59).
Systems costs (costing block C)
To estimate the costs of scaling-up coverage, we use country-specific variables to define likely production function rules for each component. The main assumptions and variables used for each component (both capital and recurrent costs) include a country classification used by the McKinsey31 consulting firm in a report to the GAVI Alliance on barriers to immunization systems performance, the Commission on Macroeconomics in Health infrastructure index,32 a transportation index based on types of available transport and communication,33 district-level vaccine coverage and country-reported immunization-specific indicators.34 The McKinsey classification groups countries into three types: TU or “turn around” countries, low performers where major system strengthening is required; SI, “strategic intervention” countries, middle performers in need of targeted interventions; and SA, “stand alone” countries, higher performers with good infrastructure. The classification is based on an assessment of political and financial commitment, physical infrastructure and equipment availability, monitoring and information systems, human resource availability and social mobilization strategies.31
Table 3 presents a summary of these assumptions. For example, the percentage of districts with less than 50% DTP3 vaccine coverage is used as an indicator as to whether additional supervisory visits at the district level are required. Media and information, education and communication costs are based on whether the country has reported an existing budget for social mobilization (and, hence, these costs were included in the baseline systems costs, rather than being new costs). Transportation costs related to the cold chain are linked to estimates of the average distance between facilities at the national, provincial, district and health service delivery levels, with the transport quartile33 determining the type of vehicle to be used and the average distance that can be travelled daily.
The analysis builds on a large database of parameters developed for the WHO-CHOICE35 project, e.g. country-specific prices for factor inputs such as stationery, fuel and other macro- and microeconomic parameters needed. Prices for immunization-specific items are obtained from Product Information Sheets.36 Additional quantities are determined for items such as outreach personnel based on analysis of country financial sustainability planning documents.19
Campaign costs (costing block D)
Delivery costs per person vaccinated, exclusive of cost of vaccines and vaccine supplies, in the different types of campaigns are based on data collected from several different country-level costing studies37–42 as well as those reported in the FSPs.19 The unit costs per person targeted include training, cold chain equipment, social mobilization, waste management, salaries and per diem and transport costs.
Where a cost per person targeted, by campaign, is available for a country, we used that estimate; where it was unavailable, we estimated the costs by using averages across WHO subregions and regions, or by extrapolating the ratio between costs of other types of campaigns in another country and applying that to a single campaign cost estimate from the country. Measles catch-up (nine months to 14 years) and follow-up campaigns (nine months to four years) were estimated to cost between US$ 0.19–1.68 per person targeted. Campaigns associated with the introduction of yellow fever (nine months and up) and meningococcal vaccines (nine months to 29 years) ranged between US$ 0.17–1.53 per person targeted; and campaigns to reduce the burden of maternal and neonatal tetanus (targeted towards women of childbearing age, 15–49), were estimated to cost US$ 0.19–1.51 per person targeted.
- Table 2. Vaccine cost assumptions, 2005–2015 [pdf]
- Table 3. Basic assumptions and cost categories for system scale-up costs [pdf]
The total cost for immunization from 2006 to 2015, including the costs to maintain the existing immunization system, is estimated to be US$ 35.5 billion in the 72 GAVI Alliance-eligible countries (range: US$ 13–40 billion), of which 54% maintains current immunization efforts and the remaining 46% is for scaling-up (5% campaigns, 16% systems, 25% vaccines). This shows a considerable shift in the distribution of spending from systems to vaccines as more expensive vaccines are introduced: of the costs to maintain current routine immunization, 25% are for vaccines; in scaling up, 60% of the costs are for vaccines.
Applying the same methods (despite the potential limitations) to the remaining 45 lower-middle-income countries, we estimate an overall cost of US$ 76.1 billion (range: US$ 23–110 billion). Among the 45 lower-middle-income countries that are not GAVI Alliance-eligible, where baseline systems costs are estimated to be higher, 71% of the projected costs for 2006–2015 are for maintaining the current programmes, of which 13% goes towards vaccines; of the scaling-up costs, 69% will be for vaccines (Table 4).
In GAVI Alliance-eligible countries, on average US$ 0.54 per capita (range: US$ 0.21–3.11 across countries), or US$ 24 (range: US$ 7–105) per child born, needs to be spent to maintain current immunization levels, varying with population size, DTP3 coverage and economic status. This needs to be nearly doubled to achieve the GIVS goals, resulting in a cost per capita of US$ 1.18 (range: US$ 0.78–4.01), or cost per child of US$ 46 (range: US$ 27–167). This is comparable to the estimated spending level of the 45 lower-middle-income countries to maintain their current immunization levels.
Estimated spending on immunization in the 72 poorest countries has risen between 2000 and 2005, from an average of US$ 1.1 billion (range: US$ 0.9–1.6) in 2000 to US$ 2.5 billion (range: US$ 1.8–4.2) in 2005.10 Despite using a different methodology, the year 2000 results are remarkably consistent with estimates from other approaches of US$ 1.1 billion in low-income countries in 2000,43 and US$ 1.17 billion (range: US$ 0.717–1.48 billion)44 in 2001.
The composition of immunization activities relative to baseline costs will differ depending on the timing of vaccine introduction. The highest-performing countries, which introduce new vaccines earlier, will need relatively more cold-chain training and supervision investment compared (34% and 22%, respectively, of systems costs) to the late introducers of new vaccines, whose current immunization systems are not as strong (18% and 4%, respectively) and who need to make more substantial investments in core areas such as personnel and outreach (2% and 5% for high performers/early introducers; 21% and 23% for low performers/late introducers). In addition, the average incremental systems costs of scaling-up per child is more in the latter group (US$ 9) than the former (US$ 8), while the average incremental vaccine costs are lower (US$ 13) for late introducers than for early introducers (US$ 23). Our findings that US$ 16.2 billion is required to scale up immunization in the 72 poorest countries over the next 10 years are sensitive to underlying assumptions. As an example, we have assumed that the cold chain volume of a rotavirus vaccine will be 11.5 ml per dose, but the currently available presentation is nearly 112 ml per dose. If the larger vial size had been used in the costing, then an additional US $1.9 billion would be required, doubling the costs of scaling-up the cold chain, and increasing associated vehicle and transportation costs by 60%.
For the subset of GAVI Alliance-eligible countries, Table 5 shows the breakdown of projected costs for each immunization activity by WHO region. The largest proportions are in the African (34%) and South-East Asian (46%) Regions. This reflects the size of the birth cohorts, as these regions have 35% and 47% of the 2005 GAVI Alliance-eligible birth cohorts, respectively.
A primary use of these costing figures is to provide a better understanding of where financing gaps will occur, to start mobilizing the necessary resources to achieve the GIVS. We assume an optimistic funding scenario based on available data18,19,45–47 from national programmes, the GAVI Secretariat and the WHO Polio Team, and the funding gaps are shown in Table 5.
For the 72 GAVI Alliance-eligible countries, about US$ 25 billion is estimated to be available for the 2006–2015 period, of which 16% is projected to come from national governments, 15% from the GAVI Alliance and 40% from external donors. Between 30% and 40% of need is unmet, an annual shortfall of more than US$ 1 billion.
The main unfunded area during the 2006–2015 period is vaccines. However, this becomes the case only when new vaccines become available in the longer term. In the medium term, the main unfunded elements will be for reaching more children, through strengthening systems and campaigns (Table 5). Regionally, the largest funding gaps in absolute terms are in the South-East Asia and African Regions; by percentage, the largest gap is in the Eastern Mediterranean Region.
- Table 4. Estimated costs of immunization in 117 low- and lower-middle-income countries, 2006–2015 [pdf]
- Table 5. Projected costs and distribution of costs of increasing the coverage of traditional and underused vaccines and health systems requirements to reach the GIVS goals by 2015 in 72 GAVI Alliance-eligible countries, together with funding gaps [pdf]
Putting a cost estimate to an immunization vision, 2006–2015 is no doubt subject to uncertainty around the data and methods used, individual strategies chosen by each country to reach its visions, price uncertainties around vaccines and other inputs to national immunization programmes, and the availability of funds to finance continuous expansions and improvements of immunization. The uncertainty bounds around the cost estimates reflect these limitations. These costing figures should be taken as indicative approximations of what it may take to scale up immunization to reach GIVS goals over the next decade. The estimates for lower–middle-income countries have additional limitations due to much of the input data for predicting baseline costs, and price data for vaccines, being specific to poorer countries.
A further limitation of this analysis is that only a finite set of potential immunization interventions is included. The newly licensed human papillomavirus vaccine is not included, nor are vaccines against seasonal influenza, nor are global public goods, including research and development, global capacity to assist countries in crisis situations with stockpiles of vaccines (e.g. for cholera). All of these are possible strategies identified in the GIVS2 and many of them will be pursued. There is a need to periodically update this costing exercise to reflect the strategies being pursued at the country level, and our improved understanding of the dynamics of immunization costing and financing. Nonetheless, the present analysis is based on realistic and rigorous assumptions, the best available data (as of 2005), and fills an important gap in knowledge.
Recognizing these limitations, we estimate that reaching immunization goals is achievable at a cost of US$ 35 billion during 2006–2015. By 2015, more than 70 million children in the world’s 72 poorest countries can be protected annually against 14 major childhood diseases if an additional US$ 1 billion per year can be invested towards immunization.10 This equates to an additional US$ 0.5 per capita per year above current levels (< US$ 1 per capita) of investment in immunization.
At such modest costs and high benefits, immunization continues to be one of the best values for public health investment today.44 Not only do immunizations save lives, but in impoverished countries they boost economies, potentially yielding a rate of return of up to 18%.48 In addition, immunization can serve as a platform to strengthen health systems and deliver other life-saving interventions such as those against malnutrition, malaria and intestinal worms.
Despite being a good buy for the health sector, financing for immunization remains a significant challenge. A funding gap of between US$ 11 billion and US$ 15 billion is estimated to remain if the goal of saving 10 million more lives is to be achieved by 2015. This financing challenge exists despite the favourable context of significant additional new resources for immunization that are available through the GAVI Alliance, IFFIm,8 the AMC9 and other global efforts. There are growing concerns about the financial sustainability of future immunization efforts, and for many of the poorest countries, shared financial responsibility between national governments and international donors will be required.49
In late 2005, WHO and UNICEF, together with GAVI Alliance partners launched the comprehensive Multi-Year Plan (cMYP) process for immunization with tools to estimate the financial requirements and gaps for reaching national goals in line with the GIVS.50 The cMYP process is a first step in translating the global into the local: a national immunization plan to implement appropriate strategies at country level. With the implementation of these plans, countries are paving the way towards sustainability of their current programmes and preparing themselves for the later generations of vaccines and technologies where financing requirements will grow.
The real challenge will hinge on how national governments, WHO, UNICEF and the international community at large, manage their roles and responsibilities in reaching and financing the goals of the GIVS until 2015. ■
- Bilous J, Eggers R, Gasse F, Jarrett S, Lydon P, Magan A, et al. A new global immunisation vision and strategy. Lancet 2006;367:1464-6.PMID:16679143 doi:10.1016/S0140-6736(06)68625-X10.1016/S0140-6736(06)68625-X
- GIVS. global immunization vision and strategy 2006–2015. Geneva; UNICEF/WHO: October 2005. Available at: http://www.who.int/vaccines-documents/DocsPDF05/GIVS_Final_EN.pdf
- UNICEF. A world fit for children: Millenium Development Goals. Special session on children documents: the convention on the rights of the child. July, 2002. Available at: http://www.unicef.org/publications/index_4445.html
- Godal T. Viewpoint: immunization against poverty. Trop Med Int Health 2000;5:160-6.PMID:10747277 doi:10.1046/j.1365-3156.2000.00534.x10.1046/j.1365-3156.2000.00534.x
- Muraskin W. The Global Alliance for Vaccines and Immunization: is it a new model for effective public-private cooperation in international public health? Am J Public Health 2004; 94: 1922-5.
- Wittet S. Introducing GAVI and the Global Fund for children’s vaccines. Vaccine 2000;19:385-6.PMID:11027798 doi:10.1016/S0264-410X(00)00196-110.1016/S0264-410X(00)00196-1
- Lu C, Michaud CM, Gakidou E, Khan K, Murray CJ. Effect of the Global Alliance for Vaccines and Immunisation on diphtheria, tetanus, and pertussis vaccine coverage: an independent assessment. Lancet 2006;368:1088-95.PMID:16997663 doi:10.1016/S0140-6736(06)69337-910.1016/S0140-6736(06)69337-9
- International Financial Facility for Immunization (IFFIm) program overview. Global Alliance for Vaccines and Immunization: 2006. Available at: http://www.gavialliance.org/resources/FS_IFFIm_en.pdf
- Advance market commitments for Vaccines. Global Alliance for Vaccines and Immunization: 2007. Available at: http://www.vaccineamc.org/about/index.html
- Saving 10 million more lives through immunization; the price tag, the shortfall. WHO/IVB: 2006. Available at: http://www.who.int/immunization/givs/GAVI_Imm_Forum_piece.pdf
- World Development Indicators 2004. The World Bank; Washington, DC: 2004.
- GAVI eligible countries. Global Alliance for Vaccines and Immunization. Available at: http://www.gavialliance.org/Support_to_Country/Who_can_Apply/eligible_countries.php
- State of the world’s children 2007.New York; UNICEF: 2006. Available at: http://www.unicef.org/sowc07/
- Wolfson LJ. WHO ICE-T: immunization coverage estimates and trajectories. Geneva; WHO: 2005.
- Measles mortality reduction and regional elimination strategic plan 2001–2005. Geneva: WHO/UNICEF: 2001. Available at: http://www.who.int/vaccines-documents/docspdf01/www573.pdf
- Maternal and neonatal tetanus elimination by 2005. Strategies for achieving and maintaining elimination. New York; UNICEF, WHO, UNFPA: November 2000. Available at: http://www.who.int/vaccines-documents/DoxGen/H3DoxList.htm
- MNT elimination: programmatic update. Geneva; WHO: 2006. Available at: http://www.who.int/immunization_monitoring/diseases/MNTE_initiative/en/index2.html
- Financial Sustainability Planning Process GAVI. Geneva: WHO; c2005. Available at: http://www.who.int/immunization_financing/analyses/fsp/process/
- National Financial Sustainability Plans. Geneva: WHO; c2005. Available at: http://www.who.int/immunization_financing/countries/
- About the costing information at National Financial Sustainability Plans. Geneva: WHO; c2005. Available at: http://www.who.int/immunization_financing/data/about/cost/
- Kumaranayake L. The real and the nominal? Making inflationary adjustments to cost and other economic data, Health Policy and Planning; 15(2): 230–234 Oxford University Press 2000.
- Box GEP, Cox DR. The analysis of transformations. J R Stat Soc [Ser A] 1964; 26: 211-52.
- Carroll RJ, Ruppert D. Transformation and weighting in regression. London; Chapman and Hall: 1988.
- World population prospects: the 2002 revision, 2004. United Nations Population Division. Available at: http://www.un.org/esa/population/publications/wpp2002/wpp2002annextables.PDF
- Seber GAF. Linear regression analysis. New York; Wiley: 1977.
- Breiman L, Friedman JH. Estimating optimal transformations for multiple regression and correlation. (with discussion). J Am Stat Assoc 1985; 80: 580-619.
- Tibshirani R. Estimating transformations for regression via additivity and variance stabilization. J Am Stat Assoc 1988; 83: 394-405.
- Furnival GM, Wilson RW. Regressions by leaps and bounds. Technometrics 1974; 16: 499-511.
- Seber GAF. Linear Regression Analysis. New York; Wiley: 1977.
- DeRoeck D, Bawazir SA, Carrasco P, Kaddar M, Brooks A, Fitzsimmons J, et al. Regional group purchasing of vaccines: review of the Pan American Health Organization EPI revolving fund and the Gulf Cooperation Council group purchasing program. Int J Health Plann Manage 2006;21:23-43.PMID:16604847 doi:10.1002/hpm.82210.1002/hpm.822
- McKinsey Consulting. Report to the GAVI Board, April 2004.
- Ranson MK, Hanson K, Oliveira-Cruz V, Mills A. Constraints to expanding access to health interventions: an empirical analysis and country typology. J Int Dev 2003; 15: 15-39.
- Limao N, Venables AJ. Infrastructure, geographical disadvantage, transport costs, and trade. World Bank Econ Rev 2001; 15: 451-79.
- Vaccine-Preventable Diseases WHO. Monitoring System 2005 Global Summary. Geneva: WHO; 2005. Available at: http://www.who.int/immunization_monitoring/data/en/
- Choosing Interventions that are Cost Effective (WHO-CHOICE). Geneva: WHO; c2004. Available at: http//www.who.int/choice
- WHO/UNICEF Product information sheets. Geneva: WHO; 2000 (WHO/V&B/00.13). Available at: http://www.who.int/vaccines-documents/DocsPDF00/www518.pdf
- Vijayaraghavan M, Lievano F, Cairns L, Wolfson L, Nandy R, Ansari A, et al. Economic evaluation of measles catch-up and follow-up campaigns in Afghanistan in 2002 and 2003. Disasters 2006;30:256-69.PMID:16689921 doi:10.1111/j.0361-3666.2006.00318.x10.1111/j.0361-3666.2006.00318.x
- Dayan GH, Cairns L, Sangrujee N, Mtonga A, Nguyen V, Strebel P. Cost-effectiveness of three different vaccination strategies against measles in Zambian children. Vaccine 2004;22:475-84.PMID:14670330 doi:10.1016/j.vaccine.2003.07.00710.1016/j.vaccine.2003.07.007
- Muchiri S. Cost-effectiveness of Measles Supplementary Immunization Activities in Kenya-Presentation made at the WHO/UNICEF Global Meeting for Measles Mortality Reduction, 15 October 2003, Cape Town, South Africa.
- Tsogbe K. Measles campaign cost-effectiveness analysis. Rwanda Measles Campaign, September 11-14, 2001. UNICEF Regional Office for Eastern and Southern Africa, Kenya. [Unpublished manuscript.]
- Uzicanin A, Zhou F, Eggers R. Economic analysis of the 1996-1997 mass measles immunization campaigns in South Africa. Vaccine 2004;22:3419-26.PMID:15308367 doi:10.1016/j.vaccine.2004.02.04210.1016/j.vaccine.2004.02.042
- Griffiths UK, Wolfson L, Quddus A, Younus M, Hafiz R. Incremental cost-effectiveness of supplementary immunization activities to prevent neo-natal tetanus in Pakistan. Bull World Health Organ 2004; 82: 643-51.
- State of the World’s Vaccines and Immunizations. Geneva: WHO; 2002.
- Brenzel L, Wolfson LJ, Fox–Rushby J, Miller M, Halsey NA. Vaccine–Preventable Diseases. Disease Control Priorities in Developing Countries. 2nd edn. New York: Oxford University Press; 2006. pp. 389-412.
- Measles Investment Case II. Submitted to the Global Alliance for Vaccines and Immunization. The Measles Partnership; June 2005. Available at: http://www.gavialliance.org/resources/16brd_05._Measles_investment_case.pdf
- Investment Case for Maternal and Neonatal Tetanus Elimination. Submitted to the Global Alliance for Vaccines and Immunization. WHO and UNICEF; June 2005. Available at: http://www.gavialliance.org/resources/16brd_06._MNT_investment_case.pdf
- Yellow Fever Stockpile Investment Case: submitted to the Global Alliance for Vaccines and Immunization. The Yellow Fever Task Force ; December 2005.
- Bloom DE, Canning C, Weston M. The value of vaccination. World Econ 2005; 6: 15-39.
- Kaddar M, Lydon P, Levine R. Financial Challenges of Immunization: A look at GAVI. Bull World Health Organ 2004; 82: 697-702.
- A new approach to planning for immunization: WHO-UNICEF guidelines for developing a comprehensive multi-year plan (cMYP). Geneva: WHO; 2005. Available at: http://www.who.int/immunization_financing/tools/cmyp
- Cold chain. Logistics for health worksheets. Geneva: WHO; 1995 (EPI/WHO/LHIS/95.01-05).
- Immunization in practice Module 3: The Cold Chain. Geneva: WHO; 2004 (WHO/IVB/04.06). Available at: http://www.who.int/vaccines-documents/iip/
- Guideline for establishing or improving primary and intermediate vaccine stores. Geneva: WHO; 2002 (WHO/V&B/02.34). Available at: http://www.who.int/vaccines-documents/DocsPDF02/www715.pdf
- Griffiths UK. The costs of waste management of sharps at immunization activities: A case study at South Africa. Geneva: WHO; 2003. [Unpublished.]
- Lydon P. Costing of Waste Management West Pacific Region. Case Study: Sicim Incinerator in Kompong Chnang Province, Cambodia. Geneva: WHO; 2002. [Unpublished.]
- Human Resources for Immunization, Report to GAVI Board, November 18-19, 2002, Dakar, Senegal.
- Initiative for Vaccine Research, World Health Organization, 20 avenue Appia, 1211 Geneva 27, Switzerland.
- United Nations Children’s Fund (UNICEF), New York, NY, United States of America.
- Department of Equity, Poverty and Social Determinants of Health, World Health Organization, Geneva, Switzerland.
- Department of Immunization, Vaccines and Biologicals, World Health Organization, Geneva, Switzerland.
- Department of Health Systems Financing, World Health Organization, Jakarta, Indonesia.