A Novel Prophylaxis Strategy Using Ecotin as A Promising Adjuvant for Fc-RBD Fusion Protein Vaccine of SARS-CoV-2Yakun Sun#, Rui Zheng#, Deyu Li#,Yitai Fang#, Liangyan Zhang, Xiaolan Yang, Wenjing Yu, Yeqing Tu, Dan Lu, Deyan Luo*, Hui Wang*Department of Infection Immunity&Defense, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, ChinaCorrespondence to:Dr. Hui Wangwanghui_dyx@hotmail.com20 Dongda Street, Fengtai District, Beijing 100071, ChinaTel: +86 10 66948532; Fax: +86 10 66948532Dr Deyan Luoldy612@126.com20 Dongda Street, Fengtai District, Beijing 100071, ChinaTel: +86 10 66948549; Fax: +86 10 66948532#These authors contributed equally to this article.