Health authorities and drug regulators in the U.S. are conveying more concerns about rare but severe blood clots associated with Johnson & Johnson's COVID-19 vaccine.

On Thursday, a Centers for Disease Control and Prevention (CDC) advisory panel unanimously gave a preferential recommendation to the Moderna and Pfizer-BioNTech vaccines over Johnson & Johnson's one-shot vaccine. Also this week, the Food and Drug Administration updated its fact sheet for health care providers who administer the J&J vaccine, citing current evidence that "supports a causal relationship between" blood clots and the J&J shot. At least 54 cases of of blood clots after receipt of the J&J vaccine have been reported in the U.S. to date. Seven women and two men, ranging in age from 28 to 62, died from the clots; another two deaths are suspected to be linked to the vaccine. The U.S. has administered roughly 17 million J&J doses. The two-shot vaccines from Moderna and Pfizer use mRNA technology, while the J&J shot is built on "more traditional virus-based technology." In April, health officials recommended a nationwide pause on administration of the vaccine due to concerns about blood clots. The pause was lifted 10 days later.

Outlets across the spectrum covered the news prominently and with a similar emphasis on the deaths linked to J&J's vaccine. Some on the right highlighted previous concerns about J&J's vaccine. Some on the left focused on how weakened support for J&J's vaccine could undermine public confidence in COVID-19 vaccines.