SHANGHAI (TIP): US drugmaker Pfizer Inc said it would cease its vaccines sales operations in China after an import licence for one of its top-selling treatments, the only vaccine it sold in the country, was not renewed.

A Pfizer spokeswoman declined to say why the Chinese import licence for Prevenar, an anti-bacterial treatment, had not been renewed. The China Food and Drug Administration regulatory agency could not immediately be reached for comment.

The move comes as drugmakers face growing difficulties obtaining approvals for medicines in China, the world’s No. 2 drug market, where pharmaceutical executives say over-stretched regulators have added more red tape to the process of bringing drugs to market.

“Based on a careful assessment of this situation, we have decided to cease our vaccines commercial operations in China at this time, effective immediately,” Pfizer spokeswoman Trupti Wagh said in comments emailed to Reuters.

Prevenar is the only vaccine Pfizer sells in China, and the move doesn’t affect its other operations in the country.

Strong growth in China sales of drugs including Prevenar helped Pfizer offset weaker global revenue growth last year.

Pfizer’s vaccines sales team has around 200 staff and “most colleagues will be impacted”, Wagh added. Pfizer has over 9,000 employees in China, according to its website, working in business segments including research and development, prescription drugs and consumer health products.

China’s fast-growing healthcare market is a magnet for global drugmakers, medical device firms and hospital operators, all keen to get a slice of a medical bill estimated to hit $1 trillion by 2020. Drug spending alone is set to hit $185 billion by 2018, according to IMS Health.

However, China’s drug approval backlog jumped a third last year, authorities said earlier this month, reflecting rising industry concern that it is getting harder to get medicines approved.

Wagh said Pfizer would work with Chinese regulators to bring Prevenar 13 – an updated version of the vaccine -to market at some point in future, although she added there was no clear timeframe for this.

Pfizer’s global revenues from the Prevenar family of products, which includes Prevenar, was $4.5 billion last year, up 12 percent against 2013, the firm said in its annual report. This included “strong operational growth” in China.

Prevenar is used to help prevent pneumococcal disease, a bacterial infection which can lead to illnesses such as pneumonia, meningitis and sepsis, according to the National Foundation for Infectious Diseases. It is the only vaccine approved to treat children under two years-old for the condition in China, Pfizer’s Wagh said.

The World Health Organization estimates there were around 14.5 million cases of serious pneumococcal disease in 2000, resulting in nearly 1 million deaths of young children.