(Yicai) Jan. 10 -- Shares of Zhifei Biological Products, Merck Sharp & Dohme’s vaccine agent in China, plunged after China’s National Medical Products Administration has approved MSD’s application to reduce the doses of its nine-valent human papillomavirus vaccine for girls nine to 14 years old.

Zhifei [SHE: 300122] closed 5.6 percent down at CNY52.32 (USD7.29) in Shenzhen today, after earlier sinking as much as 9.1 percent.

Girls aged nine to 14 in China can now receive two doses of MSD’s Gardasil 9 vaccine instead of three, the US pharmaceutical giant announced yesterday. Women between 15 and 46 years old still need to receive three shots.

A single dose of HPV vaccine can reach a similar effect as two or three doses, so girls between nine and 20 years old are recommended to take one or two shots, while women aged over 20 are advised to take two, the World Health Organization said in April 2022.

Afterward, HPV vaccine makers started pushing for a reduction in doses. China approved in May 2022 UK firm GlaxoSmithKline Pharmaceutical’ application to cut the doses of its bivalent HPV vaccine for girls aged nine to 14 to two from three. The jab hit the market in April last year. Chinese companies Wantai Biological Pharmacy and Walvax Biotechnology were also allowed to provide a two-dose bivalent HPV vaccine for females aged nine to 14.

The higher valency an HPV vaccine has, the more HPV subtypes it can protect against. Gardasil 9 is the only nine-valent HPV vaccine licensed globally. MSD applied to the Chinese regulator to use Gardasil 9 in men last September.

Chongqing-based Zhifei is the sole agent of MSD’s HPV vaccines in China. It reported revenue of CNY24.4 billion (USD3.4 billion) in the first half of last year, up 33 percent from a year earlier. Agent products contributed 96 percent of its total sales in the period.

Editors: Dou Shicong, Futura Costaglione