Current global vaccine and drug efforts against COVID-19: Pros and cons of bypassing animal trials.

COVID-19 has become one of the biggest health concern, along with huge economic burden. With no clear remedies to treat the disease, doctors are repurposing drugs like chloroquine and remdesivir to treat COVID-19 patients. In parallel, research institutes in collaboration with biotech companies have identified strategies to use viral proteins as vaccine candidates for COVID-19. Although this looks promising, they still need to pass the test of challenge studies in animal models. As various models for SARS-CoV-2 are under testing phase, biotech companies have bypassed animal studies and moved to Phase I clinical trials. In view of the present outbreak, this looks a justified approach, but the problem is that in the absence of animal studies, we can never predict the outcomes in humans. Since animal models are critical for vaccine development and SARS-CoV-2 has different transmission dynamics, in this review we compare different animal models of SARS-CoV-2 with humans for their pathogenic, immune response and transmission dynamics that make them ideal models for vaccine testing for COVID-19. Another issue of using animal model is the ethics of using animals for research; thus, we also discuss the pros and cons of using animals for vaccine development studies.