Nurses inject human papilloma virus (HPV) 9-valent vaccine for Shi Jiayu from Beijing at Boao Super Hospital United Family Boao Clinic in Boao, south China's Hainan Province, May 30, 2018. The first batch of HPV 9-valent vaccines in Chinese mainland are put into injection on Wednesday. (Xinhua/Guo Cheng)

A nurse from Boao Super Hospital United Family Boao Clinic presents a human papilloma virus (HPV) 9-valent vaccine in Boao, south China's Hainan Province, May 30, 2018. The first batch of HPV 9-valent vaccines in Chinese mainland are put into injection on Wednesday. (Xinhua/Guo Cheng)