ABSTRACT: The World Health Organization states that about 773 million people were infected by SARS-CoV-2 and the death toll touched about 7.4 million, although both the incidence and mortality crossed WHO observation. Several vaccines have been developed to counter SARS-CoV-2 and medicines of multiple disciplines have been used in COVID-19 patients. It is not unlikely another virus like SARS-CoV-2 may induce another pandemic the globe. In this pretext, we initiated some studies to develop a new and novel therapeutic that is endowed with both preventive and curative purposes. A new area of novel drug development against COVID-19 was formulated by discovering a novel agent that induce both innate and adaptive immunity and act beyond virus specificity. During the COVID era, we checked the preventive and therapeutic nature of a vaccine containing an antigen of hepatitis B virus (hepatitis B surface antigen, HBsAg) with a strong adjuvant (hepatitis B core antigen, HBcAg) (both GMP level and usable in human) by administering via nasal route (preferential mucosal route). Clinical trial in 2000 and 2022 cited its potential preventive and therapeutic activities against SARS-CoV-2 and COVID-19, especially in downregulating progression of diseases. The studies of mechanisms indicated its capacity of inducing and regulating proinflammatory and anti-inflammatory cytokines when administered via nose. We have further worked on more potent antigens, adjuvants and easy-to-use devices. The present communication would unmask the mechanism of action of this multipurpose vaccine with comparative assessment of utility of other preventive and therapeutic modalities in COVID-19 patients to optimize drug development machineries against this pathology of pandemic of viruses that enter via nose or other mucosal areas. This will ultimately indicate that a preventive and therapeutic intervention may be possible even when antigens of the responsible virus is elusive and thus a procedure would be realized to fight epidemics and pandemics during their initial stages. KEYWORDS: COVID-19, Pre-and Post-Exposure Prophylaxis, Therapeutic Vaccine.