Review of Current Vaccine Development Strategies to Prevent Coronavirus Disease 2019 (COVID-19).

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) outbreak that started in Wuhan, China, in 2019 resulted in a pandemic not seen for a century, and there is an urgent need to develop safe and efficacious vaccines. The scientific community has made tremendous efforts to understand the disease, and unparalleled efforts are ongoing to develop vaccines and treatments. Toxicologists and pathologists are involved in these efforts to test the efficacy and safety of vaccine candidates. Presently, there are several SARS-CoV-2 vaccines in clinical trials, and the pace of vaccine development has been highly accelerated to meet the urgent need. By 2021, efficacy and safety data from clinical trials are expected, and potentially a vaccine will be available for those most at risk. This review focuses on the ongoing SARS-CoV-2 vaccine development efforts with emphasis on the nonclinical safety assessment and discusses emerging preliminary data from nonclinical and clinical studies. It also provides a brief overview on vaccines for other coronaviruses, since experience gained from these can be useful in the development of SARS-CoV-2 vaccines. This review will also explain why, despite this unprecedented pace of vaccine development, rigorous standards are in place to ensure nonclinical and clinical safety and efficacy.