Seasonal Influenza Vaccine Effectiveness in a Tropical Developing African Country

热带非洲发展中国家季节性流感疫苗的有效性

• 批准号: 7673296
• 负责人: John Christian Victor
• 金额: $ 141.29万
• 依托单位: PATH
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7673296
• 关键词: Seasonal; Influenza; Vaccine; Effectiveness; Tropical

DESCRIPTION (provided by investigator): Influenza is a major cause of morbidity and mortality nearly every year; when pandemics occur, the impact is even more severe. A pandemic virus may result from reassortment of human viruses with animal influenza viruses carrying avian influenza genes. Such reassortment may occur more readily in tropical climates where human and animal viruses frequently co-circulate throughout the year. Few data are available to document the transmission and burden of influenza in tropical developing countries. Without a better understanding of influenza epidemiology in such situations, it is difficult for national and global public health officials to develop influenza control strategies for either seasonal or pandemic influenza. Effective inactivated influenza vaccines have been available for decades, but data are lacking on their effectiveness for both protecting recipients in tropical developing countries and also their ability to reduce transmission in such populations. A number of reports from developed countries indicate that influenza vaccine, when given to a limited number of persons most responsible for transmission, usually children, has the potential to interrupt transmission and reduce the overall influenza burden in a community. The potential of influenza vaccine to provide indirect protection to unvaccinated individuals suggests that targeted use, which may be feasible in developing country settings, might reduce influenza infection in the community. In a pandemic situation, these efforts could slow the spread of pandemic virus and provide sufficient time for public health officials to introduce interventions to contain or blunt the effects of a pandemic. Thus, to evaluate the effectiveness of trivalent inactivated influenza vaccine in a tropical developing country, we propose to conduct an observer-blind, cluster-randomized, active-control, parallel-group, phase IV trial in Senegal. The trial will take place over a three-year period and will target children 6 months to 10 years of age for vaccination. Not only will effectiveness be estimated for child vaccine recipients, but indirect effectiveness will also be measured for the rest of the community. Throughout the course of the study, both sentinel and active surveillance will be conducted to document the occurrence of influenza-like illness among participants and in the community. The primary outcome will be prevention of symptomatic laboratory-confirmed influenza meeting a case definition. Surveillance will also allow us to describe the epidemiology of influenza in a tropical developing country by defining the rates of laboratory-confirmed influenza and by describing the clinical characteristics of influenza in the population.

描述（由研究者提供）：流感几乎每年都是发病和死亡的主要原因；当流行病发生时，影响更为严重。大流行性病毒可能是人类病毒与携带禽流感基因的动物流感病毒重配所致。这种重排可能更容易发生在人类和动物病毒全年共同传播的热带气候中。很少有数据可以记录热带发展中国家流感的传播和负担。在这种情况下，如果不能更好地了解流感流行病学，国家和全球公共卫生官员就很难制定针对季节性或大流行性流感的流感控制策略。有效的灭活流感疫苗已问世数十年，但缺乏关于其保护热带发展中国家接种者的有效性以及减少此类人群传播能力的数据。来自发达国家的一些报告表明，当向有限数量的对传播负有最大责任的人（通常是儿童）接种流感疫苗时，有可能阻断传播并减少社区的总体流感负担。流感疫苗为未接种疫苗的个体提供间接保护的潜力表明，有针对性的使用在发展中国家可能是可行的，可能会减少社区的流感感染。在大流行情况下，这些努力可以减缓大流行病毒的传播，并为公共卫生官员提供足够的时间采取干预措施来遏制或减弱大流行的影响。因此，为了评估三价灭活流感疫苗在热带发展中国家的有效性，我们建议在塞内加尔进行观察者盲法、整群随机、主动对照、平行组、IV 期试验。该试验将持续三年，针对 6 个月至 10 岁的儿童进行疫苗接种。不仅将评估儿童疫苗接种者的有效性，还将测量社区其他人的间接有效性。在整个研究过程中，将进行哨点和主动监测，以记录参与者和社区中流感样疾病的发生情况。主要成果将是预防符合病例定义的有症状的实验室确诊流感。监测还将使我们能够通过定义实验室确诊流感的发生率和描述人群中流感的临床特征来描述热带发展中国家的流感流行病学。