Department of Public Health, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, Netherlands.
Vaccine. 2011 Aug 18;29(36):6100-6. doi: 10.1016/j.vaccine.2011.06.059. Epub 2011 Jun 22.
The only successful HIV vaccine trial to date is the RV144 trial of the ALVAC/AIDSVAX vaccine in Thailand, which showed an overall incidence reduction of 31%. Most cases were prevented in the first year, suggesting a rapidly waning efficacy. Here, we predict the population level impact and cost-effectiveness of practical implementation of such a vaccine in a setting of a generalised epidemic with high HIV prevalence and incidence.
We used STDSIM, an established individual-based microsimulation model, tailored to a rural South African area with a well-functioning HIV treatment and care programme. We estimated the impact of a single round of mass vaccination for everybody aged 15-49, as well as 5-year and 2-year re-vaccination strategies for young adults (aged 15-29). We calculated proportion of new infections prevented, cost-effectiveness indicators, and budget impact estimates of combined ART and vaccination programmes.
A single round of mass vaccination with a RV144-like vaccine will have a limited impact, preventing only 9% or 5% of new infections after 10 years at 60% and 30% coverage levels, respectively. Revaccination strategies are highly cost-effective if vaccine prices can be kept below 150 US$/vaccine for 2-year revaccination strategies, and below 200 US$/vaccine for 5-year revaccination strategies. Net cost-savings through reduced need for HIV treatment and care occur when vaccine prices are kept below 75 US$/vaccine. These results are sensitive to alternative assumptions on the underlying sexual network, background prevention interventions, and individual's propensity and consistency to participate in the vaccination campaign.
A modestly effective vaccine can be a cost-effective intervention in highly endemic settings. To predict the impact of vaccination strategies in other endemic situations, sufficient knowledge of the underlying sexual network, prevention and treatment interventions, and individual propensity and consistency to participate, is key. These issues are all best addressed in an individual-based microsimulation model.
迄今为止，唯一成功的 HIV 疫苗试验是泰国的 RV144 试验，该试验使用 ALVAC/AIDSVAX 疫苗，总体发病率降低了 31%。大多数病例在第一年得到预防，表明疗效迅速减弱。在此，我们预测在 HIV 流行率和发病率较高的普遍流行环境下，实际实施这种疫苗对人群的影响和成本效益。
我们使用了 STDSIM，这是一种成熟的基于个体的微观模拟模型，针对南非农村地区进行了定制，该地区拥有运作良好的 HIV 治疗和护理计划。我们估计了对所有 15-49 岁人群进行一轮大规模疫苗接种的影响，以及对年轻人（15-29 岁）进行 5 年和 2 年疫苗接种的策略。我们计算了预防新感染的比例、成本效益指标以及综合 ART 和疫苗接种计划的预算影响估计。
一轮大规模 RV144 样疫苗接种的影响有限，在 60%和 30%覆盖率下，分别只能预防 10 年后新感染的 9%或 5%。如果疫苗价格能保持在每剂 150 美元以下，对于 2 年的加强针策略，以及每剂 200 美元以下，对于 5 年的加强针策略，那么加强针策略的成本效益非常高。当疫苗价格保持在每剂 75 美元以下时，通过减少对 HIV 治疗和护理的需求而实现净成本节约。这些结果对基本性网络、背景预防干预措施以及个人参与疫苗接种活动的倾向和一致性的替代假设敏感。
在高度流行的环境中，一种适度有效的疫苗可以成为一种具有成本效益的干预措施。为了预测疫苗接种策略在其他流行环境中的影响，对基本性网络、预防和治疗干预措施以及个人参与的倾向和一致性有足够的了解是关键。这些问题都可以在基于个体的微观模拟模型中得到最好的解决。
