On Apr. 2, 2020, an international collaboration of virologists at the University of Wisconsin-Madison and the vaccine companies FluGen and Bharat Biotech began the development and testing of a unique vaccine against COVID-19 called CoroFlu.

CoroFlu was to be developed on the backbone of FluGen’s flu vaccine candidate known as M2SR. Based on an invention by UW-Madison virologists and FluGen co-founders Yoshihiro Kawaoka and Gabriele Neumann, M2SR is a self-limiting version of the influenza virus that induces an immune response against the flu.