登革疫苗的新發展

Progress in the Dengue Vaccine

登革熱是全世界最嚴重的蟲媒傳染病毒性疾病，每年約有5億人次的登革病毒感染，50萬人因重症而住院，2萬5千人因而死亡。台灣雖非登革熱本土流行的地區，但每年由境外移入、進一步導致散播感染的案例，也多在一千人次左右；2015年的大流行，更造成四萬人以上的感染、228人死亡。登革熱的防治，可說是全世界極為重要的課題。疫苗的發展，向來是控制病毒性傳染病很重要的一環。過去登革熱疫苗的研發，一直不是很成功；直到近年來，TV005活性減毒四價疫苗的問世，帶來了令人振奮的成果。過去的研究顯示，接種一劑TV005疫苗的成年人（18到50歲），約有90%的人可以同時對四種血清型的登革病毒產生抗體，疫苗的耐受性也很不錯。但過去TV005疫苗，鮮少針對年齡50到70歲的族群進行試驗，在此一年齡族群的免疫生成力與安全性資料都不足。而在台灣，大約超過40%感染登革熱的人是屬於50到70歲族群的人；因此，深入瞭解TV005疫苗在50歲到70歲的人群上之效果與安全性，對於台灣地區是否可以引進TV005疫苗，以為登革熱防治之用，是刻不容緩的。因此TV005疫苗在台灣進行了第二期、雙盲性、多中心、安慰劑對照之臨床試驗，初步發現250名接受試驗用藥注射的受試者，大部分之局部設定記錄不良事件（local solicited AE）及全身性設定記錄不良事件（General solicited AE）均為輕微（mild），最常見的全身性設定不良事件為皮疹，其次為倦怠，第三為肌肉痠痛。因此若後續免疫生成力有良好的成果，將有機會為台灣高齡民眾提供安全及有效的疫苗。（感控雜誌2021:31:123-128）

Dengue is the most prevalent mosquito-borne viral disease worldwide, causing 500,000 severe infections and leading to 25,000 deaths every year. Although Taiwan is not endemic to dengue, approximately 1,000 infections emerge every year because of epidemics induced by imported patients. In 2015, there was a major outbreak, with over 40,000 infections and 228 deaths. Prevention of dengue is a global health concern. The development of an effective and safe vaccine is the best solution to control viral diseases. After overcoming many hurdles, the dengue vaccine TV005, a live attenuated tetravalent vaccine, was developed. Approximately 90% of adults aged 18-50 years could develop protective immunity against all four serotypes of the dengue virus after a single dose of the TV005 vaccine. However, the immunogenicity and safety of TV005 among people aged 50-70 years are yet unclear. In Taiwan, people aged 50-70 years account for over 40% of those affected by dengue every year. Therefore, understanding the immunogenicity and safety of the TV005 vaccine among people aged 50-70 years is important to determine whether or not TV005 can be introduced in Taiwan as a major intervention to control dengue. Currently, TV005 is undergoing a phase-II, double-blind, multicenter, placebo-controlled trial in Taiwan. In the initial report of 250 participants, most local and general solicited adverse events were mild. The most common adverse events were skin rash, malaise, and muscle ache. In the future, if the trial can reveal good immunogenicity among participants, can provid evidence to support the use of TV005 among the elderly population in Taiwan to prevent dengue.