Under the public healthcare system, each vaccination usually costs about 1,300 yuan ($188), while in private facilities, the cost is typically at least 1,000 yuan more for three doses.

However, because demand heavily outstrips supply, successfully making an appointment with either public or private service providers to receive the 9-valent vaccine can be compared to winning a lottery.

In fact, in Shenzhen, Guangdong province, health authorities have been relying on a lottery system since November to fairly decide reservations for the vaccine.

When the city's health authority opened online reservations in September, the website received more than 3 million daily page views, with the number rising to 9 million in October, while only 600 to 1,000 doses were available every month.

There have been media reports of customers lining up to be placed on a waiting list when supplies run out in a particular area, or paying large amounts to agencies at home and overseas to get the vaccine, only to end up with smuggled or counterfeit supplies.

For Chen, it took less than five minutes for a nurse to administer the vaccine, but the process involved in reaching that stage took considerably longer.

She searched online for advice on how to increase the chance of a successful appointment, and then spent an afternoon in March trying to secure a reservation at community medical centers and hospitals providing the vaccination service.

She received constant rejections for more than an hour because the centers and hospitals had run out of supplies. Finally, a community medical center far from her home placed her on a shortlist.

Some two weeks later, she received a phone call asking her to come in for a vaccination at her convenience.

"I had expected to wait even longer, or go to Hong Kong for the vaccination, because I was about to turn 26," she said.

As women resort to a number of measures to receive the 9-valent vaccine, they neglect the other two types available to protect against HPV.

There are more than 100 types of HPV, and some that are closely related to the development of malignant tumors are categorized as high-risk.