(Yicai Global) July 17 -- GDK Biotechnology’s shares fell by their daily trading limit after the flu vaccine maker said it had stopped production at some workshops because of heavy rainfall in China, likely leading it to have no operating income this quarter, with the impact on annual sales still unknown.

GDK [SHA: 688670] plunged 20 percent to CNY29.35 (USD4.10) apiece in Shanghai today. The stock has tumbled 43 percent since June 14.

GDK suffered flooding and seepage after recent heavy rains in the high-tech pharmaceutical zone in Taizhou, Jiangsu province, where the firm is based, it said late on July 14. Some workshops were affected, with vaccine production to be halted from July 15 after environmental monitoring and risk assessment, it added.

All of GDK's revenue came from flu vaccines in recent years. Income from such jabs was CNY204 million (USD28.5 million) in the third quarter of last year, equal to 64 percent of its annual total, while the figure was CNY317 million in the same period of 2021, accounting for 81 percent.

Influenza vaccines have strong seasonal demand, with sales usually peaking from September to December, as strains can mutate each year and require annual inoculation. Jabs are only useful for a year after production, so those made this year can only be sold in the next 12 months.

GDK is out of stock for the upcoming flu season, with the company saying that the strains and standards for the 2023-2024 season came later than usual this year, leading to a delay in its production schedule. The temporary halt caused by the rains further delayed its product launch, which is unlikely to happen in September and be available during the peak sales season.

Editor: Martin Kadiev