Effect of probiotics as an immune modulator for the management of COVID‑19.

COVID-19, an acute respiratory viral infection conveyed by pneumonia caused by severe acute respiratory syndrome coronavirus
2 (SARS-CoV-2), has affected millions of individuals globally, and is a public health emergency of international
concern. Till now, there are no highly effective therapies for this infection without vaccination. As they can evolve quickly
and cross the strain level easily, these viruses are causing epidemics or pandemics that are allied with more severe clinical
diseases. A new approach is needed to improve immunity to confirm the protection against emerging viral infections. Probiotics
can modify gut microbial dysbiosis, improve the host immune system, and stimulate immune signaling, increasing
systemic immunity. Several probiotic bacterial therapies have been proven to decrease the period of bacterial or viral infections.
Superinduction of inflammation, termed cytokine storm, has been directly linked with pneumonia and severe complications
of viral respiratory infections. In this case, probiotics as potential immunomodulatory agents can be an appropriate
candidate to improve the host’s response to respiratory viral infections. During this COVID-19 pandemic, any approach that
can induce mucosal and systemic immunity could be helpful. Here, we summarize contexts regarding the effectiveness of
various probiotics for preventing virus-induced respiratory infectious diseases, especially those that could be employed for
COVID-19 patients. In addition, the effects of probiotics, their mechanisms on different aspects of immune responses against
respiratory viral infection, and their antiviral properties in clinical findings have been described in detail.