The role of early HIV infection in the spread of HIV through populations
The role of early HIV infection in the spread of HIV through populations
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DOI：
10.1097/00042560-199703010-00009
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发表时间：
1997-03-01
期刊：
影响因子：
--
通讯作者：
Lange, K
中科院分区：
文献类型：
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作者：
Koopman, JS;Jacquez, JA;Lange, K
两个因素的结合使早期艾滋病毒感染对传播动态产生了特别强的影响：（a）传播概率增加和（B）在此期间受感染的伴侣的传播潜力增加。大多数注意力都集中在第一个因素上，因为它符合我们通常认为影响个人的风险因素的方式。第二个因素不是作用于个人，而是跨越传播链。在个体一生中伴侣关系形成率恒定或随机混合的模型中，这一点被忽略了。它不能从个人收集的现有数据进行评估。它的评估需要来自伙伴关系中的两个人的数据。我们证明，这第二种效果可以是如此强大，早期感染可以主导传输动态，即使传输概率只有适度增加。这第二个效果是不直接参数化在我们的模型中，但产生于两个现实类型的时间变化的伙伴关系的形成：（a）伙伴关系的形成率随年龄而变化，在自己的年龄组的优惠伙伴关系的形成，和（B）任何年龄的个人可以经历短暂的时期的高风险的伙伴关系的形成。在一个模型中，只有年龄相关的影响，观察到早期感染占主导地位的传播动力学时，20%的传染性病毒被分配到感染的前6周，7%的中期感染，73%的晚期感染。这种控制既发生在流行病的早期，也发生在后来达到地方性感染水平时。当添加第二个效应时，在将10%的可传播病毒分配给前6个月，40%分配给中期感染，50%分配给晚期感染的模型中，早期感染被视为主导传播。在该模型中，早期感染的传播概率仅为中期感染的4.17倍，晚期感染的一半。
The combination of two factors gives early HIV infection an especially strong influence on transmission dynamics: (a) increased transmission probabilities and (b) increased transmission potential of partners infected during this period. Most attention has been focused on the first factor because it fits the way we usually think about risk factors affecting individuals. The second factor acts not on individuals, but across chains of transmission. It is missed by models with constant partnership formation rates over an individual's life or with random mixing. It cannot be assessed from available data collected from individuals. Its assessment requires data from both individuals in a partnership. We demonstrate that this second effect can be so strong that early infection can dominate transmission dynamics even when transmission probabilities are only modestly increased. This second effect is not directly parameterized in our models but arises from two realistic types of temporal variation in partnership formation: (a) Partnership formation rates vary by age with preferential partnership formation in one's own age group, and (b) individuals of any age can experience transient periods of high-risk partnership formation. In a model with only the age-related effect, early infection is observed to dominate transmission dynamics when 20% of transmissible virus is allocated to the first 6 weeks of infection, 7% to middle infection, and 73% to late infection. This domination occurs both early in the course of an epidemic and later when endemic infection levels have been reached. When the second effect is added, early infection is seen to dominate transmission in a model allocating 10% of transmissible virus to the first 6 months, 40% to middle infection, and 50% to late infection. In this model, transmission probabilities during early infection are only 4.17 times those of middle infection and half those of late-stage infection.