Ethicists and physicians are concerned that, amid a desire to put an end to the Covid-19 pandemic, developers of drugs and vaccines have become overly enthusiastic about the chances their products will work. While several vaccine developers have issued statements looking into the future -- setting possible timetables for study completion and vaccine manufacturing -- the ethicists and doctors say one group in particular stands out as being the most aggressive in painting the rosiest picture: the University of Oxford in England.