Chinese syringe makers are warning that they may only be able to fulfil some orders as late as June, as global coronavirus vaccination programmes put unprecedented levels of pressure on their factory lines and snarl the country's own vaccine efforts.

Companies told Reuters that they were working around the clock, raising prices and trying to expand factory lines. China and India are the world's biggest producers of syringes, industry executives said.

Zhejiang KangKang Medical Devices began receiving export contracts for 10 million to 20 million syringes each in December, compared with order sizes of about 5 million each before the pandemic, thanks to overseas vaccination programmes, Guo Chun, its general manager, told Reuters.

The company, a unit of Wanbangde Pharmaceutical Holding , was adding capacity to quadruple its production for certain types of syringes by May, but until then can only partly fulfil large orders, he said.

“We are very careful in taking in new orders now,” said an office manager surnamed Yang at another manufacturer, Shandong Qiaosen, a supplier to Becton Dickinson that is based in the northern Chinese city of Shandong. He declined to give his full name.