The other day, I was video chatting with my walking buddy, Jo, about viruses and plagues—what else?—and I explained (with no shortage of passion) how if humanity is to be ended by pandemic, this whole get-put-on-a-ventilator-for-weeks-until-life-slowly-drains-out-of-you gets a giant Boo Hiss from me. The human race warrants a more proficient viral assassin, I said. Like maybe a heartstopper. Something fast, but not too gross.