(Yicai) Aug. 27 -- Shares of Chinese influenza vaccine makers soared after French pharmaceutical giant Sanofi said it would suspend the supply and sale of its two flu jabs in the Chinese market for the time being.

Hualan Biological Vaccine [SHE: 301207], China's biggest flu shot producer, surged by its 20 percent daily trading limit to close at CNY18.86 (USD2.65) a share in Shenzhen today, while GDK Biotechnology [SHA: 688670] jumped 19.9 percent to CNY12.80 in Shanghai trading.

Sanofi notified Jiahui Health and other Chinese medical institutions earlier today that it was temporarily halting the supply of its trivalent and quadrivalent influenza vaccines. Yicai learned from Sanofi that the reason was the declining effectiveness of the two jabs during this year's flu season.

China’s flu season typically occurs in two peaks: one in the winter (December to February) and another in the spring (March to May), with these cycles vary slightly depending on the region.

The inoculations received sales approval from local regulators and fully complied with local laws, rules, and drug standards, Paris-based Sanofi noted, adding that it did not find any indication or evidence that product safety and efficacy had been impacted.

The demand for flu vaccines in China has surged in recent years, with factors such as increased public awareness, government initiatives to promote inoculation, and the lingering impact of the Covid-19 pandemic each driving higher vaccination rates.

International companies such as Sanofi have traditionally supplied flu vaccines in China’s highly competitive market for the jabs, but domestic players such as Hualan and GDK have gained ground thanks to their local production capabilities, competitive pricing, and rapid approval processes.

Sanofi has introduced more than 60 novel drugs and vaccines to the Chinese market since its entry in 1982. In the first half of this year, the company's sales in China rose 3 percent to EUR1.5 billion (USD1.7 billion) from a year earlier, accounting for 7 percent of Sanofi's global sales.

Net profit at Hualan surged 65 percent to CNY860 million (USD120.7 million) last year, according to the Henan province-based firm's annual earnings report. Revenue jumped 32 percent CNY2.4 billion (USD336.9 million), over 99 percent of which came from its flu shots business.

Editors: Dou Shicong, Futura Costaglione