Some infectious disease experts are considering whether Johnson & Johnson's coronavirus vaccine - known for only requiring one dose - may actually need a booster shot of a different vaccine to deal with the more contagious Delta variant of the disease.
The group includes Andy Slavitt, a former senior pandemic advisor to President Biden. Some of those experts say they've already given themselves a booster, despite a lack of data on whether it's safe to do so.
Reuters spoke with Jason Gallagher, an infectious disease expert at Temple University, who combined his Johnson & Johnson shot with a dose of the Pfizer vaccine. He said he was concerned over studies from the United Kingdom that show single doses aren't as effective at fighting the Delta variant, which was originally found in India and has spread rapidly.
At least half a dozen prominent experts say the issue needs to be addressed, and quickly.
The UK studies show that two doses of the Pfizer/BioNTech and AstraZeneca vaccines are significantly more effective against the Delta variant than one dose. The Moderna vaccine is also being trialed as a possible booster by the U.S. government.