More than 50 million cattle are likely exposed to bovine tuberculosis (bTB) worldwide, highlighting an urgent need for bTB control strategies in low- and middle-income countries (LMICs) and other regions where the disease remains endemic and test-and-slaughter approaches are unfeasible. While Bacillus Calmette-Guérin (BCG) was first developed as a vaccine for use in cattle even before its widespread use in humans, its efficacy against bTB remains poorly understood. To address this important knowledge gap, we conducted a systematic review and meta-analysis to determine the direct efficacy of BCG against bTB challenge in cattle, and performed scenario analyses with transmission dynamic models incorporating direct and indirect vaccinal effects (“herd-immunity”) to assess potential impact on herd level disease control. The analysis shows a relative risk of infection of 0.75 (95% CI: 0.68, 0.82) in 1,902 vaccinates as compared with 1,667 controls, corresponding to a direct vaccine efficacy of 25% (95% CI: 18, 32). Importantly, scenario analyses considering both direct and indirect effects suggest that disease prevalence could be driven down close to Officially TB-Free (OTF) status (<0.1%), if BCG were introduced in the next 10-year time period in low to moderate (<15%) prevalence settings, and that 50–95% of cumulative cases may be averted over the next 50 years even in high (20–40%) disease burden settings with immediate implementation of BCG vaccination. Taken together, the analyses suggest that BCG vaccination may help accelerate control of bTB in endemic settings, particularly with early implementation in the face of dairy intensification in regions that currently lack effective bTB control programs.

全球有超过 5000 万头牛可能暴露于牛结核病 (bTB)，这突显了在低收入和中等收入国家 (LMIC) 以及该疾病仍然流行并采用检测和屠宰方法的其他地区制定 bTB 控制策略的迫切需求是不可行的。虽然卡介苗 (BCG) 在广泛用于人类之前就首先被开发为用于牛的疫苗，但其对抗 bTB 的功效仍知之甚少。为了解决这一重要的知识差距，我们进行了系统回顾和荟萃分析，以确定 BCG 对牛 bTB 攻击的直接功效，并使用包含直接和间接疫苗效应（“群体免疫”）的传播动态模型进行情景分析评估对畜群疾病控制的潜在影响。分析显示，与 1,667 名对照组相比，1,902 名接种者的感染相对风险为 0.75（95% CI：0.68, 0.82），对应于 25% 的直接疫苗效力（95% CI：18, 32）。重要的是，考虑直接和间接影响的情景分析表明，如果在未来 10 年期间以低至中度引入 BCG，疾病流行率可能会降低到接近正式无结核病 (OTF) 状态 (<0.1%) (<15%) 的流行设置，并且即使在高 (20-40%) 的疾病负担环境中，如果立即实施卡介苗疫苗接种，也可以在未来 50 年内避免 50-95% 的累积病例。综上所述，分析表明卡介苗接种可能有助于加速流行环境中 bTB 的控制，