Health service centers have reassured women who have had the first one or two doses of a four-way HPV vaccine - which requires three doses within six months - that they have full supplies.

Concerns arose after recent media reports that the four-way HPV vaccine Gardsil, which works against four types of HPV and has been available in major cities on the Chinese mainland since the end of last year, was highly sought after and many centers had canceled reservations because they were out of stock.

"The suspension of new reservations is just to guarantee the required doses for those who have received the first one or two," said a woman who only gave her surname, Zhang, from the Xuhui district's Kangjian community health service center in Shanghai.

Each time the center is replenished with, say 30 doses, it will provide them to 10 women to ensure each can obtain her three doses as scheduled, she said.

There are already 200 women with reservations on the waiting list and it is hard to tell how long they will have to wait, Zhang said.

The Obstetrics and Gynecology Hospital of Fudan University said the vaccines were booked up just days after the inoculation became available in Shanghai in March.

"Our stock can guarantee that the 171 women who have received the first dose can have their second shot - suggested at two months after the first dose. Our stocks will get replenished in July or August so there is no worry about their third shot - suggested at six months after the first," said Shen Yan from the hospital's publicity department.

Xiong Ying, a physician with Shanghai-based Sino-United Health Clinic, said it is fine if the three doses are finished over a span of 12 months.

Wang Qing, director of the cervical disease diagnosis and treatment center at the Obstetrics and Gynecology Hospital of Fudan University, said: "I suggest that women who plan to get the inoculation sign a contract with the health center that the three doses must be received within one year, since the shortage of the vaccine seems severe."

Local news portal thepaper.cn cited officials from the Shanghai Center for Disease Control and Prevention as saying the shortage of the vaccine is mainly due to high market demand.

In late April, China's top drug administration approved the import of the latest HPV vaccine, which works against nine types of HPV, into the mainland.