Reuters: J&J Vaccine Drive Stalls Out In U.S After Safety Pause Safety concerns about Johnson & Johnson's (JNJ.N) COVID-19 vaccine along with overall flagging demand for vaccinations have slowed its U.S. rollout to a crawl, leaving close to half of the 21 million doses produced for the United States sitting unused. J&J's vaccine was supposed to be an important tool for reaching rural areas and vaccine hesitant Americans because it requires only one shot and has less stringent storage requirements than the two-dose vaccines from Pfizer Inc/BioNTech SE and Moderna Inc. (Erman, 6/7)