Poletti Piero, Merler Stefano, Ajelli Marco, Manfredi Piero, Munywoki Patrick K, Nokes D, Melegaro Alessia
BMC Med. 2015 Mar 10;13:49. doi: 10.1186/s12916-015-0283-x.
Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract disease and related hospitalization of young children in least developed countries. Individuals are repeatedly infected, but it is the first exposure, often in early infancy, that results in the vast majority of severe RSV disease. Unfortunately, due to immunological immaturity, infants are a problematic RSV vaccine target. Several trials are ongoing to identify a suitable candidate vaccine and target group, but no immunization program is yet in place.
In this work, an individual-based model that explicitly accounts for the socio-demographic population structure is developed to investigate RSV transmission patterns in a rural setting of Kenya and to evaluate the potential effectiveness of alternative population targets in reducing RSV infant infection.
We find that household transmission is responsible for 39% of infant infections and that school-age children are the main source of infection within the household, causing around 55% of cases. Moreover, assuming a vaccine-induced protection equivalent to that of natural infection, our results show that annual vaccination of students is the only alternative strategy to routine immunization of infants able to trigger a relevant and persistent reduction of infant infection (on average, of 35.6% versus 41.5% in 10 years of vaccination). Interestingly, if vaccination of pregnant women boosts maternal antibody protection in infants by an additional 4 months, RSV infant infection will be reduced by 31.5%.
These preliminary evaluations support the efforts to develop vaccines and related strategies that go beyond targeting vaccines to those at highest risk of severe disease.
呼吸道合胞病毒（RSV）是最不发达国家幼儿下呼吸道疾病及相关住院治疗的主要病因。个体可反复感染，但绝大多数严重的RSV疾病是由首次接触病毒引起的，这种接触通常发生在婴儿早期。不幸的是，由于免疫不成熟，婴儿是RSV疫苗接种的难题对象。目前正在进行多项试验以确定合适的候选疫苗和目标群体，但尚未实施免疫计划。
在这项研究中，开发了一个明确考虑社会人口结构的个体模型，以调查肯尼亚农村地区RSV的传播模式，并评估不同人群目标在减少RSV婴儿感染方面的潜在效果。
我们发现家庭传播导致39%的婴儿感染，学龄儿童是家庭内的主要感染源，引发约55%的病例。此外，假设疫苗诱导的保护作用与自然感染相当，我们的结果表明，对学生进行年度疫苗接种是能够引发婴儿感染显著且持续减少的唯一替代常规婴儿免疫的策略（平均而言，在10年的疫苗接种期间，分别为35.6%和41.5%）。有趣的是，如果孕妇接种疫苗能使婴儿获得额外4个月的母体抗体保护，RSV婴儿感染将减少31.5%。
这些初步评估支持了开发疫苗及相关策略的努力，这些策略不仅针对高风险严重疾病人群，还包括其他群体。
