Costs and Cost-Effectiveness of Adding New Antigens to the Current Immunization Schedule
We also estimated the additional costs per person vaccinated and cost per death averted of introducing new and underused vaccines into the traditional EPI in a hypothetical population of 1 million in each region between 2002 and 2011. The new vaccines considered protect against hepatitis B, yellow fever, Hib, measles, rubella, Japanese encephalitis, and meningococcal A, as well as inactivated polio vaccine (IPV). For comparison purposes, we assumed that new vaccines were introduced in 2002.
The additional cost of combination vaccines is net of the original cost of DTP vaccination to avoid duplication. The delivery cost per FIC was apportioned to individual antigens on the basis of the share of number of doses per FIC for that antigen (Brenzel 2005). Cost estimates are based on the number of doses required for full immunity (that is, hepatitis B, Hib, and IPV vaccines require three doses for full immunity, and meningococcal A requires two doses for full immunity). Results are reported in table 20.6.
The analysis also assumes that an additional visit to a health facility is required for new doses (depending on timing in the EPI schedule).Combination vaccines may be more cost-efficient because of potential savings in supplies, syringes, and health workers' time, in addition to the overall health benefits of reducing the number of required injections. However, if the combination vaccine does not reduce the number of visits a child would ordinarily need to make to a health facility, any cost savings may be subsumed by the higher costs of increasing coverage.
The discounted incremental cost per person ranges from less than US$1 to US$16.23, depending on the unit price of vaccine, the type of vaccine, the delivery strategy, and the coverage levels. The results lead to several conclusions:
First, the additional incremental cost per person vaccinated is relatively small for some new vaccines.
Second, because fixed costs are excluded, the results represent conservative estimates of additional costs.
Third, because of price uncertainty, cost variations are greatest for newer vaccines, such as the DTP-IPV combination.
The second opportunity for measles has the lowest cost per death averted, ranging from US$23 to US$1,906 for fixed facility strategies, and from US$65 to US$1,363 for campaigns These results are consistent with the literature. Foster, McFarland, and John (1993) find an incremental cost per death averted ranging from US$335 to US$552 in urban areas and from US$327 to US$706 in rural areas. The Africa Measles Partnership (2004) estimates a cost per death averted of US$131 to US$393 in the African context, but these figures include the costs of infrastructure.
In the hypothetical populations, the incremental cost per death averted for the pentavalent vaccine ranged from US$1,319 in Sub-Saharan Africa to more than US$42,500 in Europe and Central Asia, depending mostly on the number of potential deaths that could be averted. Although a wide range of results was found, these estimates are supported by the literature. Miller (1998) estimated between US$3,127 and US$3.2 million per life saved for Hib vaccine. Brinsmead, Hill, and Walker's (2004) systematic review of the literature on the cost-effectiveness of Hib vaccine finds wide variations in results because of methodological differences and epidemiological and health system characteristics. The discounted incremental cost of introducing the pentavalent (DTP-hepatitis B-Hib) vaccine is roughly equal to the total mean cost of the traditional vaccine package estimated earlier. This finding implies that introducing this combination vaccine may double the financial requirements, an implication that is supported by data from national financial sustainability plans for immunization (Lydon 2004).
The incremental discounted cost per person vaccinated with a birth dose of hepatitis B is approximately US$2, and that for the tetravalent vaccine was between US$7 and US$8. The 10-year time period for our analysis is too short to accumulate deaths averted resulting from hepatitis B vaccination because deaths from liver cancer occur at older ages. Beutels's (1998, 2001) reviews of studies of the cost-effectiveness of introducing hepatitis B vaccine indicate that results vary depending on assumptions of endemicity and the methodology used, with a cost per death averted ranging from US$3,500 to US$271,800.
Rubella vaccination had a low additional cost per person vaccinated, at slightly more than US$1. Golden and Shapiro (1984) found that vaccinating all prepubertal children with rubella vaccine had the highest benefit-cost ratio (ranging from US$1.70 to US$1.96). Most benefits were future cost savings from long-term institutional care. When rubella was delivered in combination with measles and mumps, the benefit-cost ratios varied from US$4.70 to US$38.80 (Hinman and others 2002).
The additional cost per person vaccinated with one dose of Japanese encephalitis vaccine was between US$4.37 and US$4.56. A study in Thailand using two doses showed a cost per child ranging from US$2.31 to US$4.20, depending on the mode of delivery (Siraprapasiri, Sawaddiwudhipong, and Rojanasuphot 1997). Ding and others (2003) estimate a cost per case averted of US$258 and a cost per DALY averted of US$16.80 for a five-dose inactivated Japanese encephalitis vaccine.
Our analysis suggests an additional discounted cost per person vaccinated for injectable polio vaccine of between US$6.60 and US$7.32, depending on coverage levels and mix of delivery strategy. The additional discounted unit cost of the combination DTP-IPV vaccine was higher, ranging from US$13.88 to US$15.28. These results are also sensitive to the current prices of the vaccine, which will probably decline in coming years. Brenzel (1995) finds that in India the cost per case prevented for the combination DTP-polio vaccine was much lower than for oral polio vaccine (OPV), primarily because the combination vaccine was associated with a greater reduction in the number of polio cases. Miller and others (1996) suggest that introducing IPV into routine vaccination in the United States would cost an additional US$15 million to US$28 million depending on the type of schedule adopted, resulting in a cost per vaccine-associated paralytic poliomyelitis case prevented of approximately US$3 million. Sangrugee, Caceres, and Cochi (2004) found that the least costly option would be for programs to stop providing OPV after postpolio eradication and certification and that optionally introducing IPV with universal IPV had the highest costs and the lowest expected number of vaccine-associated paralytic poliomyelitis cases. If the unit price of IPV fell to US$0.47, switching to IPV from OPV would be economically worthwhile.