More than 170 vaccines are being developed against COVID-19 (SARS-CoV-2) by researchers in companies and universities throughout the world. 31 vaccines are in human trials and 140 vaccines are in preclinical evaluation, according to the data from WHO, August 25 2020. There is a broad range of vaccine technologies being tried against COVID-19, from proven vaccine platforms (such as protein-subunit and viral vectors) to novel ones (such as mRNA and DNA), and they rely on different virus and viral parts.