The Wall Street Journal reported the Centers for Disease Control and Prevention (CDC) ceased availability to states, though deliveries are expected to resume.
The Journal cited health officials from several states, like Oklahoma and Illinois, who reportedly said they could not order new J&J doses in the last weeks. Some said they have enough supply.
The backlog in unused doses is allegedly due in part to an 11-day federally recommended pause in J&J vaccinations as officials probed rare reports of blood clots. The pause resulted in many canceled appointments without rescheduled time slots. When compounded with vaccine hesitancy, the pause inadvertently resulted in a pileup of unused doses.
When questioned over the report, a spokesperson at Janssen said the company is working with the government to support use of the vaccine.
"We remain committed to helping end this deadly pandemic as quickly as possible," a spokesperson at Janssen wrote in an email to Fox News. "A single-shot vaccine that provides protection and prevents hospitalization and death is a critical tool in the global fight against COVID-19. Evidence from our Phase 3 ENSEMBLE study demonstrates the efficacy of the J&J single-shot COVID-19 vaccine, including against viral variants that are highly prevalent. Regardless of race and ethnicity, age, geographic location and comorbidities, these results remain consistent."
"We continue to work with the U.S. government and health authorities to support the use of our vaccine, which continues to play an important role, including among those who wish to be fully vaccinated with one shot."
The company said a Food and Drug Administration review concluded the shots remain safe and effective up to 4 1/2 months. The announcement comes after state officials warned that many unused doses in storage would expire before the end of the month.
The Associated Press contributed to this report.