BCG turns 100 this year and while it might not be the perfect vaccine, it has certainly contributed significantly towards eradication and prevention of spread of tuberculosis (TB). The search for newer and better vaccines for TB is an ongoing endeavor and latest results from trials of candidate TB vaccines such as M72AS01 look promising. However, recent encouraging data from BCG revaccination trials in adults combined with studies on mucosal and intravenous routes of BCG vaccination in non-human primate models have renewed interest in BCG for TB prevention. In addition, several well-demonstrated non-specific effects of BCG, for example, prevention of viral and respiratory infections, give BCG an added advantage. Also, BCG vaccination is currently being widely tested in human clinical trials to determine whether it protects against SARS-CoV-2 infection and/or death with detailed analyses and outcomes from several ongoing trials across the world awaited. Through this review, we attempt to bring together information on various aspects of the BCG-induced immune response, its efficacy in TB control, comparison with other candidate TB vaccines and strategies to improve its efficiency including revaccination and alternate routes of administration. Finally, we discuss the future relevance of BCG use especially in light of its several heterologous benefits.

中文翻译：

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BCG的一个世纪：对结核病控制及未来的影响

卡介苗今年已经100岁了，虽然它可能不是完美的疫苗，但它无疑对根除和预防结核病（TB）的传播做出了巨大贡献。寻找更新和更好的结核病疫苗是一项持续的工作，候选结核病疫苗（例如M72AS01）的试验的最新结果看起来很有希望。然而，最近来自成人的BCG疫苗接种试验的令人鼓舞的数据，以及在非人灵长类动物模型中对BCG疫苗的粘膜和静脉途径进行研究的研究，重新引起了人们对BCG预防结核病的兴趣。另外，卡介苗的几种非特异性作用，例如预防病毒和呼吸道感染，也为卡介苗提供了额外的优势。还，BCG疫苗接种目前正在人类临床试验中进行广泛测试，以确定它是否可以预防SARS-CoV-2感染和/或死亡，并等待世界各地数项正在进行的试验的详细分析和结果。通过本综述，我们尝试收集有关BCG诱导的免疫反应各个方面的信息，其在结核病控制中的功效，与其他候选结核病疫苗的比较以及提高其效率（包括重新接种和替代给药途径）的策略。最后，我们讨论了BCG使用的未来相关性，尤其是从BCG的几个异源益处出发。我们尝试收集有关BCG诱导的免疫反应各个方面的信息，其在结核病控制中的功效，与其他候选结核病疫苗的比较以及提高其效率（包括再接种和其他给药途径）的策略。最后，我们讨论了BCG使用的未来相关性，尤其是从BCG的几个异源益处出发。我们尝试收集有关BCG诱导的免疫反应各个方面的信息，其在结核病控制中的功效，与其他候选结核病疫苗的比较以及提高其效率（包括再接种和其他给药途径）的策略。最后，我们讨论了BCG使用的未来相关性，尤其是从BCG的几个异源益处出发。