Abstract

The causative agent of novel coronavirus disease (COVID-19) is severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The SARS-CoV-2 possesses RNA as a genetic material with 79% of the match with the bat SARS-CoV genome, which became epidemic in 2002. The SARS-CoV-2 peripheral Spike-Fc protein binds specifically to the ACE2 receptors present on bronchial epithelial cells and alveolar pneumocytes to downmodulates its expression which leads to severe acute respiratory failure. The disease is super infectious from human to human and the symptoms are similar to flu. The old aged and immunocompromised population are severely affected, and healthcare providers globally applied various strategies for treatment including the repurposing of drugs including antimalarial drug, hydroxychloroquine and anti-viral drugs.

Herein, we described the SARS-CoV-2 pandemic, immune responses, possible drug targets, vaccines under the trials and correlated the possibility of trained immunity induced by BCG vaccination over control of SARS-CoV-2 infection. The countries with constraint BCG vaccination policy are struggling badly compared to countries with BCG vaccination policy. The BCG vaccination policy supports either lowering the total number of COVID-19 cases or the increasing recovery rate.

摘要

新型冠状病毒病 (COVID-19) 的病原体是严重急性呼吸系统综合症冠状病毒 2 (SARS-CoV-2)。SARS-CoV-2 具有 RNA 作为遗传物质，与 2002 年流行的蝙蝠 SARS-CoV 基因组的匹配率为 79%。SARS-CoV-2 外周 Spike-Fc 蛋白与存在的 ACE2 受体特异性结合对支气管上皮细胞和肺泡肺细胞进行抑制，下调其表达，导致严重的急性呼吸衰竭。这种疾病在人与人之间具有很强的传染性，症状类似于流感。老年人和免疫功能低下的人群受到严重影响，全球医疗保健提供者采取了各种治疗策略，包括重新利用抗疟药、羟氯喹和抗病毒药等药物。

在此，我们描述了 SARS-CoV-2 大流行、免疫反应、可能的药物靶点、试验中的疫苗，并将 BCG 疫苗接种诱导的训练免疫与控制 SARS-CoV-2 感染的可能性相关联。与有 BCG 疫苗接种政策的国家相比，有 BCG 疫苗接种政策限制的国家正在苦苦挣扎。BCG 疫苗接种政策支持降低 COVID-19 病例总数或提高康复率。