Sanofi has temporarily stopped distributing and selling its flu shots in China out of concerns of waning potency.
A Sanofi spokesperson confirmed the halt to Fierce Pharma. Supplies of the French pharma’s two China-approved split-virion flu shot brands, Vaxigrip and VaxigripTetra, are being affected for the ongoing 2024-25 influenza season.
Sanofi suspended the rollout after observing a decline in the vaccines’ potency—the ability of the shots to produce the intended biological effect—during a routine quality follow-up test of doses that had been produced but not yet distributed, according to the spokesperson.
“We believe the efficacy could possibly be impacted before the end of the product’s shelf life for one of the antigens in the vaccine,” the spokesperson explained.
The Vaxigrip and VaxigripTetra shots Sanofi manufactures have met good manufacturing practices and Chinese standards, and “the decision to stop their supply and sale is a preventive measure,” the spokesperson said.
“All vaccines already distributed meet the necessary specifications for release and are both safe and effective,” the spokesperson added.
Sanofi attributed the problem to “unexpected circumstances” at the company’s influenza vaccine production line in the Chinese city of Shenzhen. The issue doesn’t appear to affect other markets, according to the Sanofi spokesperson, as the Shenzhen site makes doses exclusively for China. In the U.S., Sanofi is offering flu shots under the brands Fluzone, Fluzone High-Dose, and Flublok.
Sanofi said it doesn’t expect the issue will have any major impact on overall flu protection in China. In 2023, Sanofi booked 2.67 billion euros in global flu vaccines sales, down 5.5% year over year at constant exchange rates. While the French pharma is one of the largest vaccine makers globally, the Chinese flu shot market has been dominated by local firms.
Sanofi’s hiccup comes after a round of price cuts intensified competition among flu shot manufacturers in China. Flu vaccines are not included in China’s national immunization program, and people need to pay out of pocket to get inoculated.
After state-run Sinopharm reduced its quadrivalent flu vaccine’s price by 31% to 88 Chinese yuan (about $12) per dose in May, Hualan Biological Vaccine—the largest flu shot supplier in China by volume by a large margin—and Sinovac followed suit in June. Sanofi’s quadrivalent shot VaxigripTetra competes directly with those domestic offerings.
Meanwhile, for the 2024-25 flu season, the U.S. is transitioning to trivalent flu shots rather than the more inclusive quadrivalent options after the FDA noted that the B/Yamagata lineage of the influenza virus has not been spotted worldwide after March 2020.
“Sanofi remains dedicated to supporting flu prevention in China, a commitment that has guided our efforts for nearly three decades,” the company spokesperson said. “We will continue to collaborate with our partners to ensure that influenza vaccines are available for the 2025-2026 season, protecting the health of Chinese population.”