The prevalence of COVID-19 continues to rise with more than 114,315,846 million confirmed cases and 2,539,427 deaths worldwide by 3 March 2021 and this number kept on increasing day by day. There is no clear therapeutic treatment or vaccine available for COVID-19 till date and by seeing such a high rise in the cases of COVID-19 on daily basis, it would have been necessary to implement precautions and hygienic measures to monitor and reduce human-to-human transmission of SARS-CoV-2 before there is any successful intervention/treatment available. Currently, several studies demonstrated the important improvements in both the innate and adaptive immune systems of COVID-19 patients. In particular, pre-existing research, on immune response to B cell and T cells are highlighting that pre-existing immunity exists in about 90% of the general population because of previous exposure to CoVs and having immunity against these CoVs. Although it is not clear from, the current studies on COVID-19 but it assumed that, it might have implication to COVID-19 severity and could play an important role in treatment or vaccine development against COVID-19. This review summarizes the information from occurrence of SARS-CoV-2 to its pathogenesis, transmission, adaptive immune response with respect to T cell and B cell stimulation and therapeutic interventions/treatment against COVID-19.