卡介苗

title: 历史.
content: 结核病是古老的疾病,肆虐人类超过5000年。  卡介苗疫苗的发明是来自牛痘的经验。1882年,德国人罗伯特·科赫首次发现结核杆菌,在第一次世界大战期间法国细菌学家卡迈特(Calmett)与他的助手介岚(Guerin)研发了「卡介苗(BCG)」,1919年移交给巴黎巴斯德研究所,1921年首次使用于人体上。一开始市民的接受程度并不踊跃。甚至在吕贝克,240名婴幼儿接种疫苗后,在10天内竟造成72个婴儿死亡。但后来发现,此事件中卡介苗经管已被一株储存在同一个孵化器内的菌株污染,并引发了对厂商采取法律行动。  卡介苗可说是人类历史上使用最多的疫苗,最经常使用的是由三角肌外缘皮内注射,接种时有灼痛感,一般会在注射部位形成疤痕,称之为卡疤或卡痕。卡介苗的效果在近三十年来倍受质疑。在欧洲,结核病盛行率在卡介苗广泛应用之前已明显下降,从没有广泛使用卡介苗的北美,结核病的盛行率也自然下降。广泛应用卡介苗数十年的国家,如印度和中国,结核病的盛行率并没有因为卡介苗的使用而下降。多个大型的流行病学研究也无法证明卡介苗可以预防肺结核。目前比较肯定的是,卡介苗75%～86%有效地预防婴幼儿的进行性原发性感染(progressive primary tuberculosis)如结核性脑膜炎和血行播散性结核(如粟粒性脑膜炎)等严重并发症。因此,在结核病中高度流行区,为新生儿接种卡介苗还是有其重要意义的,但不应作为控制结核病的主要措施。  按照世界卫生组织的建议,在结核病中高度流行区(22个结核病高负担国家),新生儿应尽早接种卡介苗。  成年人种卡介苗意义不大,因保护效果有限,正常成年人自身的免疫力已能在病原入侵时启动,如果还是发病表示吸入的结核菌数过多或复发性感染,当时又正好免疫能力差,而这类情形就算是先前有注射卡介苗,也一样无用,所以成人基本上没有卡介苗意义。目前多重抗药性(MDR-TB)结核菌出现导致传统卡介苗防护力更低下,科学界正在研发新型卡介苗。
title: 效果差异.
content: 卡介苗一直以来都有所谓的效果差异。在不同地理环境的临床试验具有不同的实验数据,在英国的保护作用为60%至80%。越接近赤道,疗效愈差。
title: 效果差异原因.
content: 一些可能的原因已被提出,但还没有得到证实。
title: 研究.
content: 初步研究显示,卡介苗可能对贫困地区的人口健康提供一种有益的非特定效应,略微降低死亡率和败血病及呼吸道疾病的发病率。用得年龄越早效果越好。  在恒河猴中,卡介苗经过静脉注射给药,保护率较其他方法大幅度提升。  科学家正在初步研究卡介苗对于一型糖尿病的治疗作用。  对2019冠状病毒病的研究中,纽约理工学院发现有施打卡介苗的国家2019冠状病毒病死亡率显著较低,有统计学上差异。

Summary: 卡介苗(,简称BCG,中文名称来自于其发明者卡氏-介氏)是一种最初被用于预防结核病的疫苗。在结核病常发的国家,常推荐健康的婴儿在出生时候尽快接受一剂量的卡介苗注射。但患有艾滋病的婴儿不应该注射该疫苗。而在结核病少发的地区,在有结核病可疑病例被检测及治疗时,只有高危婴儿才会注射卡介苗。未患结核病而且并未对结核病免疫,但又长期暴露在抗药性结核菌环境下的成年人也应该注射卡介苗。

BCG vaccine: Bacillus Calmette–Guérin (BCG) vaccine is a vaccine primarily used against tuberculosis (TB). In countries where tuberculosis or leprosy is common, one dose is recommended in healthy babies as close to the time of birth as possible. In areas where tuberculosis is not common, only children at high risk are typically immunized, while suspected cases of tuberculosis are individually tested for and treated. Adults who do not have tuberculosis and have not been previously immunized but are frequently exposed may be immunized as well. BCG also has some effectiveness against Buruli ulcer infection and other nontuberculous mycobacteria infections. Additionally it is sometimes used as part of the treatment of bladder cancer. Rates of protection against tuberculosis infection vary widely and protection lasts up to twenty years. Among children it prevents about 20% from getting infected and among those who do get infected it protects half from developing disease. The vaccine is given by injection into the skin. The benefit of additional doses is not supported by evidence. Serious side effects are rare. Often there is redness, swelling, and mild pain at the site of injection. A small ulcer may also form with some scarring after healing. Side effects are more common and potentially more severe in those with poor immune function. It is not safe for use during pregnancy. The vaccine was originally developed from "Mycobacterium bovis", which is commonly found in cows. While it has been weakened, it is still live. The BCG vaccine was first used medically in 1921. It is on the World Health Organization's List of Essential Medicines, the safest and most effective medicines needed in a health system. Between 2011 and 2014 the wholesale price was US$0.16 to US$1.11 a dose in the developing world. In the United States it costs US$100 to US$200. As of 2004 the vaccine is given to about 100 million children per year globally.