TMPRSS2 and infection: Antibodies against particular epitopes can enhance infection in vitro via a novel ADE mechanism in ACE2-transfected HEK293T cells, which lack TMPRSS2.Antibodies that enhance infection in vitro do not enhance infection in vivo.No strong evidence of ADE, AED or VAED following at preclinical or clinical vaccine evaluation.In studies designed to induce VAED in ferrets, Syrian hamsters and macaques, protection against disease was observed and only transient pathology was noted in ferrets.