Department of Community Medicine and School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China.
Proc Natl Acad Sci U S A. 2010 Feb 16;107(7):3269-74. doi: 10.1073/pnas.0911596107. Epub 2010 Feb 1.
Treatment strategies for severe cases of pandemic influenza have focused on antiviral therapies. In contrast, passive immunotherapy with convalescent blood products has received limited attention. We consider the hypothesis that a passive-immunotherapy program that collects plasma from a small percentage of recovered adults can harvest sufficient convalescent plasma to treat a substantial percentage of severe cases during a pandemic. We use a mathematical model to estimate the demand and supply of passive immunotherapy during an influenza pandemic in Hong Kong. If >5% of 20- to 55-year-old individuals recovered from symptomatic infection donate their plasma (donor percentage > 5%), >67% of severe cases can be offered convalescent plasma transfusion (treatment coverage > 67%) in a moderately severe epidemic (R (0) < 1.4 with 0.5% of symptomatic cases becoming severe). A donor percentage of 5% is comparable to the average blood donation rate of 38.1 donations per 1,000 people in developed countries. Increasing the donor percentage above 15% does not significantly boost the convalescent plasma supply because supply is constrained by plasmapheresis capacity during most stages of the epidemic. The demand-supply balance depends on the natural history and transmission dynamics of the disease via the epidemic growth rate only. Compared to other major cities, Hong Kong has a low plasmapheresis capacity. Therefore, the proposed passive-immunotherapy program is a logistically feasible mitigation option for many developed countries. As such, passive immunotherapy deserves more consideration by clinical researchers regarding its safety and efficacy as a treatment for severe cases of pandemic influenza.
严重流感大流行的治疗策略主要集中在抗病毒疗法上。相比之下，恢复期血液制品的被动免疫疗法受到的关注有限。我们提出了一个假设，即从一小部分康复成年人中采集血浆的被动免疫疗法方案可以收获足够的恢复期血浆，从而在大流行期间治疗大量严重病例。我们使用数学模型来估计香港流感大流行期间被动免疫疗法的需求和供应。如果有 5%以上（捐献者比例>5%）的 20-55 岁个体从有症状感染中康复并捐献其血浆，则在中度严重的流行（R(0)<1.4，有 0.5%的有症状病例发展为重症）中，超过 67%的重症病例可以接受恢复期血浆输注（治疗覆盖率>67%）。捐献者比例 5%与发达国家平均每千人 38.1 次的献血率相当。在大多数流行阶段，由于单采血浆能力受限，捐献者比例超过 15%并不会显著增加恢复期血浆的供应，因此提高捐献者比例并不能显著增加供应。供需平衡仅取决于疾病的自然史和通过流行增长率的传播动力学。与其他主要城市相比，香港的单采血浆能力较低。因此，对于许多发达国家来说，拟议的被动免疫疗法方案是一种可行的缓解措施。因此，临床研究人员应更多地考虑被动免疫疗法作为治疗严重流感大流行病例的安全性和有效性。
