Johnson & Johnson said on Thursday it is aiming to begin in September a late-stage study of its experimental vaccine for the novel coronavirus, as researchers work at break-neck speed to develop a shot to combat the fast-spreading pathogen. The New Brunswick, New Jersey-based healthcare conglomerate, which expects to start human trials of its vaccine this month, lags other companies that also are developing coronavirus vaccines, with Moderna Inc. expected to begin a late-stage study on July 27.