Immunity against COVID-19: Potential role of Ayush Kwath Shankar Gautam, Arun Gautam, Sahanshila Chhetri, Urza Bhattarai a) Ministry of Health and Population, Kathmandu, Nepal b) Ministry of Social Development, Gandaki Province, Nepal c) TU Ayurveda Teaching Hospital, Kirtipur, Nepal d) MCOMS, Pokhara, Nepal Abstract SARS-CoV-2 infection associated respiratory disease- COVID-19 has evolved into a pandemic but, being a new form of virus, pathogenesis of disease causation is not fully understood and drugs and vaccines against this virus are still being tested so that no effective drugs or vaccines have been advised by regulatory authority. In this context, the Ministry of AYUSH, Government of India has recommended ‘Ayush Kwath’ to improve the immunity and combat the infection. Our objective of this literature review is to review the role of immunity in pathogenesis of COVID-19 and role of Ayush Kwath against the virus and regulation of immunity. Current review was conducted using a search of available literature on COVID-19 and immunity, Vyadhikshamatwa, Ayurveda and COVID-19, Rasayana, Coronavirus, SARS-CoV-2, immunomodulatory effects of medicinal plants; Tulsi/Holy Basil/Ocimum sanctum, Dalchini/Cinnamon/Cinnamomum zeylanicum, Sunthi/Ginger/Zingiber officinale and Marich/Black Pepper/Piper nigrum. Ayur-veda, being an ancient science have both medicinal and cultural values and had stimulated our kitchen and influenced what we ate in different seasons and the remedies we used for common ailments. Herbs such as Tulsi, Marich, Sunthi, Dalchini are the most commonly used and easily available drugs in home. Thus, Ayush Kwath due to its immune-modulatory, antiviral, anti-oxidant, anti-inflammatory, anti-platelet, anti-atherosclerotic, hepato-protective, reno-protective properties; seems to be effective in immuno-regulation for controlling viral infections like COVID-19. Further pre-clinical and clinical trials need to be done for the evaluation of safety and efficacy of this polyherbal formulation. © 2020 The Authors. Published by Elsevier B.V. on behalf of Institute of Transdisciplinary Health Sciences and Technology and World Ayurveda Foundation. This is an open access article under the CC BY-NC-ND license 1. Introduction COVID-19, also known as severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) is an infectious disease believed to be originated from bats and transmitted to human beings [1]. Being a new form of virus, pathogenesis of disease causation is not fully understood and drugs and vaccines against this virus are still being tested so that no effective drugs or vaccines have been advised by regulatory authority. Not only for Coronavirus, have many other viruses also lack preventive vaccines and effective antiviral medications. Studies have explored that these viruses can form drug-resistant mutants, which decrease the existing drug’s efficacy. So, these viruses can be a threat to the mankind for long time [2]. High mortality among immune-compromised and those with some underlying pathology implies that the factors that improve immunity can prevent serious manifestations due to COVID-19 infection [3]. Many herbal products are found to have immune-modulatory and antiviral property, so their discovery can be a milestone in the prevention and control of COVID-19 [2]. In this context, the Government of India has recommended to take ‘Ayush Kwath’ in order to boost the immunity. As this is a new formulation, this needs to be validated scientifically. We have made an attempt to review the immune-pathogenesis of COVID-19 and the role of each herb over it. 2. Immunopathogenesis of COVID-19 The ‘S’ protein of coronavirus can bind to host cells through the ACE2 receptor found in the oral and nasal mucosa [1,4]. Other sites where ACE2 receptors are found are lungs, stomach, intestine, bladder, heart, and kidney [5]. Variable presentation of disease in different age groups, serious manifestations that are seen more commonly in immune-compromised, old aged and in those with underlying pathology, many asymptomatic cases in pediatric age group, and presence of lymphopenia in the majority of the cases; these factors implies that immunity has a vital role in the patho-genesis of COVID-19 [1,6e8]. It is assumed that our immune system has lack of memory against such a virus that gave it an edge over humans [3]. Viruses cause cell destruction mainly in two ways; direct cyto-pathic effects of the virus and immune response mediated destruction [9]. COVID-19 cannot lyse the cells directly as the major pathway of cell destruction is due to immune-mediated destruction [10,11]. It has been mentioned that unlike adults, less vigorous cell-mediated immune response in alveoli of children results in being asymptomatic in the majority of cases [3]. The pathogenesis can be split into two stages: Non-severe and Severe [12]. 2.1. Non-severe stage The virus fuses with the host cell membrane and enters inside the host cell through airway epithelium [13,14]. The virus propagates and multiplies inside the host cell and can reach lower airway and alveoli. In adults with good innate cellular and humoral immunity propagation of virus can be limited and viral load reaching alveoli can be reduced thus recovery can take place within 2e3 weeks with mild symptoms [3]. Humoral immunity prevents the viruses to enter new cells while cell-mediated immunity targets on eradicating virus-infected cells [1,15]. In this stage, a strong immune system can be helpful in preventing the propagation of the virus thus reducing the severity of the disease [12]. 2.2. Severe stage Once the immune system is breached, the virus propagates and reaches the lower respiratory tract and alveoli. Then the virus can penetrate alveoli and reaches systemic circulation causing viremia [3]. The virus binds to multiple organs having ACE2 receptor protein. During this stage, cell-mediated immunity becomes robust and starts releasing various pro-inflammatory cytokines (IFN-a, IFN-g, IL-1B, IL-6, IL-12, IL-18, IL-33, TNF-a, etc.) and chemokines (CCL2, CCL3, CCL5, CXCL8, CXCL9, CXCL10, etc.) causing damage to multiple organs known as Cytokine storm [16,17]. We may need to suppress the inflammation for improvement during this severe stage [12]. IL-6 receptor antagonist (Tocilizumab), and anti-inflammatory interleukin (IL-10) are proposed to have a thera- peutic role in the reduction of severity and mortality of COVID-19 [18,19]. As increased risk of thromboembolic phenomena is also found to be associated with COVID-19, prophylactic antithrombotic medications are advised during this stage [20]. 3. Ayurveda purview 3.1. Disease concept It seems that most early cases had a history of contact with the original market for seafood, but the disease has now advanced to