Infant MC can lower health system costs because of moderate implementation costs, high and durable protective effects, and the averted HIV-care costs. As the sensitivity analysis shows, these findings are robust across a wide range of input values for Rwanda. The study shows that adolescent MC may be a highly cost-effective intervention. MC for adults is the least cost-effective of the three procedures.
Findings are generally consistent with results from other costing studies on adult MC in Lesotho 
, Swaziland 
, and with cost-effectiveness analysis of adult MC in Uganda 
and South Africa 
, even though in these countries HIV incidence, and consequently the number of potentially averted HIV infections, is much higher. In Uganda, with an annual HIV incidence of 1.25% and a cost per adult MC of US$69 , the cost of MC (not adjusted for savings on treatment) per HIV infection averted was estimated at US$1,485 (including the indirect effect on women). The study in South Africa shows that MC generates large net savings after adjustment for averted HIV medical costs. With an annual HIV incidence of 3.8% and a cost per adult MC of US$55.7, the cost of MC (unadjusted for averted medical care costs) per HIV infection averted was estimated at US$181 (including the indirect effect on women); while for 1,000 circumcisions net savings (adjusted for averted medical care cost) were US$2.4 million.
A recent study by White et al. 
also found that MC is a cost-saving intervention in a wide range of scenarios of HIV and baseline circumcision prevalence. The authors predict that circumcising neonates, although cheaper, would only become cost-saving after around 30 y (within the time horizon of our study). These findings are consistent with ours because our model considers the net present value of the interventions, extended to the entire life of the circumcised individuals. The absolute cost per infection averted is significantly lower in the White paper than in ours, but this is to be expected given that they estimated benefits of reduced secondary infections among the sexual partners of the circumcised men, while we did not. The White paper also concludes that as neonate and adult programmes are likely to be relatively noncompetitive for staff, facilities, and training, an optimal strategy may be to scale up both simultaneously, which is also consistent with our findings, albeit for a setting with much lower incidence and prevalence.
Neonatal MC is a less expensive procedure (faster, less complicated, and with fewer side effects) than adolescent and adult circumcision and can also be cost-saving (even when considering the discounting effect). Most importantly, infant circumcision can be easily integrated into existing health services (such as neonatal visits and vaccination sessions) and, where health workers are well trained, it does not require skilled surgeons and parallel structures that could drain an already weak system. Moreover, neonatal MC may carry less risk of a compensatory increase in risky sexual behaviour and it is likely to be more protective than adolescent or adult circumcision because there is no possibility of sexual activity during healing. Finally, circumcision among children does not carry the same implications as those for adolescents and adult MC, such as discomfort, stigma, and days out of school and work (with their associated opportunity costs).
We deduce that infant circumcision has a better potential to achieve the very high coverage over time of the population required to achieve maximal reduction on HIV incidence than adolescent and adult circumcision.
This model assumes similar sized cohorts for adolescents and adults as for infants, and one might wonder why, given that the population in need of circumcision is so much larger than a single birth cohort. This was done for several reasons. First, the government policy question that prompted the study was whether infant circumcision should be added as a strategy to that already proposed for adolescents and adults. Thus, by using the size of the Rwandan birth cohort, the per-person costs could be compared with MC at other ages and the total costs and affordability of infant MC could also be assessed. Since the model does not attempt to estimate secondary benefits (e.g., to the female partners of circumcised men) or the herd effect of high levels of MC, the relative results will be the same regardless of whether the model is run with a cohort of one or 150,000. However, while 150,000 children represent a high level of annual coverage of the birth cohort, a realistic strategy for adolescent or adult catch-up should probably aim for higher annual coverage. A realistic assessment of what coverage levels could be attained, and at what cost (especially one that considered effects of scale on program costs) goes beyond the purpose of this study.
Given that this study does not quantify the indirect benefits of MC, the cost-effectiveness estimates are conservative. This is likely to be even truer for infants than for adolescents and adults for two reasons: MC coverage of infants is likely to be much higher, potentiating the herd effect, and, behavioural compensation is less likely to occur with infants.
Any modelling exercise is at best an approximation of reality. Studies that model the future, like this one, approximate a reality that does not yet exist, and this requires making a number of assumptions about the future (for instance on what will happen to HIV incidence rates, on the effectiveness of large-scale circumcision, and on the costs of HIV treatment in the future). Thus, these results, like those of similar exercises, must be seen as valuable inputs into decision-making because they identify likely impacts of different courses of action. They cannot pretend to eliminate the uncertainty that underlies such decisions, just to reduce it. As mentioned above, this model also has limitations related to what it does and does not include. The most important of these limitations is the fact that the model only takes the prevention benefit for the circumcised individual into consideration, and not for his sexual partners and offspring.
In this study we show that MC for infants is not only highly cost-effective but also likely to be cost-saving and that MC for adolescents is a cost-effective procedure. Although benefits will be gained later in life, these positive results are stronger for circumcision of male newborns. The next step for Rwanda is to explore how best to introduce MC at different ages, including an appropriate mass media campaign. A pilot implementation exercise in one district, accompanied by close monitoring and operational research on key variables, should be followed by a scale-up of the program country wide.
Given the low cost and long term benefits, this study suggests that countries with moderate HIV epidemics should offer routine infant circumcision, integrated into existing health services. In addition, adolescents should be offered MC until aging of circumcised infants renders it obsolete and adult MC should be offered with priority to population groups with a high level of HIV incidence. Owing to the increased complexity of this strategy, each country will need to consider a variety of options to achieve high levels of coverage with adolescent/adult MC. Options may include specialized centres, mobile surgery units, and specialized surgery teams that move from clinic to clinic. MC should be offered as part of an integrated HIV prevention package that includes promotion of safer sex (delayed initiation, reduction in multiple/concurrent partners, and access to condoms).
African leaders and development partners should stop managing the HIV response as only an emergency issue and release themselves from a 1-y or even a 5-y planning perspective to focus on sustainable long-term choices for countries. From a development perspective, because infant MC is proven to be an effective means of HIV prevention, action cannot be deferred simply because gains will be in the distant future. National plans should be made accordingly on the basis of the best available information, knowing that currently there is neither a vaccine nor cure for AIDS, while remaining open and flexible to adaptation if better solutions arise. In the presence of infant MC, adolescent and adult MC would evolve into a “catch-up” campaign that would be needed at the start of the program but would eventually become superfluous upon attainment of high levels of infant coverage. Infant circumcision is likely to be highly cost-effective even in countries with lower incidence than Rwanda. In Rwanda, if the dynamic benefits of circumcision (prevention of secondary infections) are considered in addition to the health benefits for the circumcised man, even adult MC is likely to be close to or below the highly cost-effective threshold. This finding suggests that Rwanda should be simultaneously scaling up circumcision across a broad range of age groups, with high priority to the very young.