A controversial scientist who carried out provocative research on making influenza viruses more infectious has completed his most dangerous experiment to date by deliberately creating a pandemic strain of flu that can evade the human immune system.

Yoshihiro Kawaoka of the University of Wisconsin-Madison has genetically manipulated the 2009 strain of pandemic flu in order for it to “escape” the control of the immune system’s neutralizing antibodies, effectively making the human population defenseless against its reemergence.