The Washington Post reports in Johnson & Johnson recipients may benefit from a booster, but perhaps a different shot, new data suggests https://www.washingtonpost.com/health/2021/10/13/johnson-and-johnson-booster-shot/ "The documents include an FDA review of Johnson & Johnson's tests of a second dose of its own vaccine and a separate preprint study that tested mixing booster doses from different companies. The data could provide a road map for the 15 million people who received Johnson & Johnson vaccine in the United States, many of whom have felt left out because the vast majority of U.S. vaccine recipients received messenger RNA vaccines from Pfizer-BioNTech or Moderna."
The preprint: https://connect.medrxiv.org/relate/content/181