The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of ongoing global pandemic of coronavirus disease 2019 (COVID-19), has infected millions of people around the world, especially the elderly and immunocompromised individuals. The infection transmission rate is considered more rapid than other deadly pandemics and severe epidemics encountered earlier, such as Ebola, Zika, Influenza, Marburg, SARS, and MERS. The public health situation therefore is really at a challenging crossroads. The internal and external and resident microbiota community is crucial in human health and is essential for immune responses. This community tends to be altered due to pathogenic infections which would lead to severity of the disease as it progresses. Few of these resident microflora become negatively active during infectious diseases leading to coinfection, especially the opportunistic pathogens. Once such a condition sets in, it is difficult to diagnose, treat, and manage COVID-19 in a patient. This review highlights the various reported possible coinfections that arise in COVID-19 patients vis-à-vis other serious pathological conditions. The local immunity in lungs, nasal passages, oral cavity, and salivary glands are involved with different aspects of COVID-19 transmission and pathology. Also, the role of adaptive immune system is discussed at the site of infection to control the infection along with the proinflammatory cytokine therapy.

中文翻译：

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COVID-19 患者中与微生物群相关的合并感染：真正的挑战

严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 是 2019 年冠状病毒病 (COVID-19) 全球持续大流行的原因，已感染全世界数百万人，特别是老年人和免疫功能低下的人。感染传播速度被认为比之前遇到的其他致命流行病和严重流行病更快，例如埃博拉、寨卡、流感、马尔堡、SARS和中东呼吸综合征。因此，公共卫生形势确实处于一个充满挑战的十字路口。内部、外部和常驻微生物群落对于人类健康至关重要，并且对于免疫反应至关重要。该群落往往会因病原体感染而发生改变，随着疾病的进展，这会导致疾病的严重程度。在导致双重感染的传染病期间，这些常驻微生物群很少会变得消极活跃，特别是机会性病原体。一旦出现这种情况，就很难诊断、治疗和管理患者的 COVID-19。本综述重点介绍了 COVID-19 患者与其他严重病理状况之间可能发生的各种可能的合并感染。肺、鼻道、口腔和唾液腺的局部免疫与 COVID-19 传播和病理学的不同方面有关。此外，还讨论了适应性免疫系统在感染部位控制感染以及促炎细胞因子治疗的作用。