Johnson & Johnson announced Thursday that the Food and Drug Administration (FDA) has authorized an extension of its COVID vaccine's shelf life from three months to 4.5 months.

Why it matters: Amid a slowdown in vaccine uptake, a number of state health officials had been sounding the alarm that hundreds of thousands of single-shot J&J doses could expire this month.

• Prior to the FDA's extension, J&J's vaccine could be stored at normal refrigeration temps for up to three months. Pfizer and Moderna's two-shot vaccines must be stored in colder temperatures, but can last for up to six months.
• The extension is based on "data from ongoing stability assessment studies, which have demonstrated that the vaccine is stable at 4.5 months when refrigerated at temperatures of 36 – 46 degrees Fahrenheit (2 – 8 degrees Celsius)," J&J said in a statement.

The FDA did not immediately respond to Axios' request for comment.

What they're saying: "A single-shot vaccine that provides protection and prevents hospitalization and death is an important tool in the global fight against COVID-19," J&J said.

• "Evidence from our Phase 3 ENSEMBLE study demonstrates the efficacy of our 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."
• Vaccine providers should check the J&J website to confirm the vaccine's latest expiration dates, the company added.

The big picture: The authorization comes as COVID vaccine demand declines in the U.S., though it continues to skyrocket abroad.

• In the U.S., over 10.1 million J&J doses have been delivered but not administered, according to CDC data.
• President Biden has said he will send 20 million doses of COVID vaccines, including Pfizer, Moderna and J&J, to other countries by the end of June.