Department of Cancer Biology, Metastasis Research Center, University of Texas MD Anderson Cancer Center, Houston, TX, USA.
Department of Systems Biology, University of Texas MD Anderson Cancer Center, Houston, TX, USA.
Sci Rep. 2020 Oct 27;10(1):18377. doi: 10.1038/s41598-020-75491-x.
The Bacillus Calmette-Guerin (BCG) vaccine provides protection against tuberculosis (TB), and is thought to provide protection against non-TB infectious diseases. BCG vaccination has recently been proposed as a strategy to prevent infection with SARS-CoV-2 (CoV-2) to combat the COVID-19 outbreak, supported by its potential to boost innate immunity and initial epidemiological analyses which observed reduced severity of COVID-19 in countries with universal BCG vaccination policies. Seventeen clinical trials are currently registered to inform on the benefits of BCG vaccinations upon exposure to CoV-2. Numerous epidemiological analyses showed a correlation between incidence of COVID-19 and BCG vaccination policies. These studies were not systematically corrected for confounding variables. We observed that after correction for confounding variables, most notably testing rates, there was no association between BCG vaccination policy and COVD-19 spread rate or percent mortality. Moreover, we found variables describing co-morbidities, including cardiovascular death rate and smoking prevalence, were significantly associated COVID-19 spread rate and percent mortality, respectively. While reporting biases may confound our observations, our epidemiological findings do not provide evidence to correlate overall BCG vaccination policy with the spread of CoV-2 and its associated mortality.
卡介苗（BCG）疫苗可预防结核病（TB），并被认为可预防非结核病传染病。BCG 疫苗接种最近被提议作为预防 SARS-CoV-2（CoV-2）感染的策略，以应对 COVID-19 疫情，这一策略得到了其增强先天免疫的潜力以及最初的流行病学分析的支持，这些分析观察到在普遍实施 BCG 疫苗接种政策的国家，COVID-19 的严重程度降低。目前有 17 项临床试验注册，以了解接触 CoV-2 时 BCG 疫苗接种的益处。许多流行病学分析显示 COVID-19 的发病率与 BCG 疫苗接种政策之间存在相关性。这些研究没有系统地校正混杂变量。我们观察到，在对混杂变量（尤其是检测率）进行校正后，BCG 疫苗接种政策与 COVD-19 传播率或死亡率百分比之间没有关联。此外，我们发现描述合并症的变量，包括心血管死亡率和吸烟率，分别与 COVID-19 传播率和死亡率百分比显著相关。虽然报告偏倚可能会影响我们的观察结果，但我们的流行病学发现并未提供证据表明总体 BCG 疫苗接种政策与 CoV-2 的传播及其相关死亡率之间存在相关性。
