Approved on July 17, 2023, AstraZeneca and Sanofi’s Beyfortus (nirsevimab-alip) occupies a unique niche as a respiratory syncytial virus (RSV) F protein-directed fusion inhibitor for neonates and infants. With RSV rates surging, the drug quickly fell into a shortage.

The CDC and FDA recently made available more than 77,000 additional doses of Beyfortus. Meanwhile, Senate Democrats Tammy Duckworth, Kirsten Gillibrand, Ron Wyden, Ed Markey, Richard Blumenthal, Jon Ossoff, and Elizabeth Warren pushed AstraZeneca and Sanofi for action regarding the supply shortage.

Unprecedented demand

Facing criticism for the supply shortfall, Sanofi noted it had encountered “higher than anticipated demand” and said it had an “aggressive supply plan” in place to exceed past performance of pediatric vaccine launches.

AstraZeneca also noted that demand for Beyfortus had “far surpassed any previous standard.”

In a recent letter, the Senators requested detailed information on the situation, along with measures to ensure equitable distribution and prevent future shortages. The Senators pressed for transparency from the manufacturers, inquiring about the timeline of awareness of the shortage, communication with the FDA, barriers to scaling up production, and the rationale behind pricing decisions. They emphasized the need for equitable access, particularly for underserved communities, and sought assurances about the availability of the 50 mg doses. The lawmakers requested a response by November 30, 2023, underscoring the urgency of the situation ahead of the RSV season.

Demand for the vaccine has been especially strong for the 100-mg dosage of Beyfortus. 

Addressing the shortfall in Beyfortus supply

Both AstraZeneca and Sanofi have committed to providing briefings on the current availability of Beyfortus and the underlying factors of the supply issues.

The 2022–2023 RSV season’s unusual timing, starting later than the prior season but earlier than pre-pandemic seasons, has also contributed chaos to the situation. The U.S typically experiences annual community outbreaks of RSV infections during the colder months, but the recent shifts in seasonality can set the stage for off-season RSV circulation.