COVID-19 Vaccines: Global Challenges and Prospects Forum ... www.sciencedirect.com/science/article/abs/pii/S... (c) Protein based vaccines, CoV RBD219-N1 Vaccine from Baylor College of Medicine, Texas that is based on a yeast-derived (Pichia pastoris) protein (Hotez and Bottazzi, 2020) and from Anhui Zhifei Longcom Biopharmaceutical Co. Ltd (Dai et al., 2020).