A Comprehensive Review of Possible Immune Responses against Novel SARS-CoV-2 Coronavirus: Vaccines Strategies and Challenges

The current deadly COVID-19 pandemic caused by the SARS-CoV-2 virus appeared in late December 2019 in Wuhan, China, and spread globally. The epidemic is still spreading, and there are no effective strategies to prevent the infection. Many companies and institutes are trying to figure out the solution by developing vaccines and antiviral drugs, but still, it requires advanced research and long times. However, scientists were able to decide that Immunological response induction is the ultimate target for any vaccine candidate. The immune response to SARS-CoV-2 involves all the immune system components that together appear responsible for viral elimination and recovery from the infection. Many immunological studies have been conducted based on T cell immunity because dependence on the antibody is not the only solution whether some studies showed that antibody wiped out very early. Some studies suggest that cytotoxic T cells and memory T cells give long term immunity. Nonetheless, the vaccines racing from the front provide promising results in various phases (preliminary to phase 2) to induce enough potent neutralizing antibodies. Besides, some vaccines showed T cell-based immune response, which may induce long-term immunity memory T cells. This review mainly illustrated potential vaccine development strategies and challenges by focusing on T-cellbased immune response against SARS-CoV-2 Coronavirus.