Introduction: The nine‐item Patient Health Questionnaire (PHQ‐9) is widely used to determine the severity of depression in adult populations, but its psychometric properties with regard to adolescents has been poorly explored. The present study aims to identify the factor structure and examine the measurement invariance of this instrument across genders and age groups in a Chinese adolescent sample.Methods: A large sample of Chinese schoolchildren completed the PHQ‐9 in a cross‐sectional survey in Hong Kong (N = 10 933). A confirmatory factor analysis (CFA) to test the factor structure and a multiple group CFA to test the gender and age invariances of the PHQ‐9 in adolescents were conducted. Cronbach alpha was used to assess the reliability of the questionnaire, and Pearson correlations with anxiety, self‐esteem, and perceived control were used to assess its construct validity.Results: The CFA results indicate that a one‐factor model with three pairs of item correlations fitted the PHQ‐9 data well, and measurement invariances by age and gender were supported. The PHQ‐9 also possesses adequate internal consistency (>.84) and is strongly correlated with anxiety (>.77), self‐esteem (<−.57), and perceived control (<−.56) in the expected directions in the overall sample and in the gender and age subsamples.Discussion: The results support the claim that the PHQ‐9 is a reliable and valid scale and can be used to assess and compare depressive severity across ages and genders during the period of adolescence.

The Human Papillomavirus (HPV) vaccine has the great potential to prevent HPV-related infections for millions of women and men worldwide. However, the success of the vaccine is highly dependent on the vaccination rate. Factors influencing the attitudes of undergraduate students towards HPV vaccination should be studied. This is a cross-sectional survey that was conducted to estimate the HPV vaccination rate among undergraduate students in Hong Kong, and to identify the predictors of their attitude towards HPV vaccination. The results showed that the HPV vaccination rate was 13.3%. Factors related to knowledge of vaccination were the main predictors of the students’ attitude towards vaccination (there were seven predictors, with B = 1.36 to 2.30; p < 0.05), followed by gender (B = −1.40; p < 0.05), acceptable maximum price (B = 0.35; p < 0.05), and willingness to receive the HPV vaccine if it can protect against cervical/anal cancer and genital warts (B = −1.90; p < 0.001). The regression model that was developed based on the predictors had a moderate effect size (adj-R² = 0.33). To conclude, the HPV vaccination rate among undergraduate students in Hong Kong was low. They should be provided with more active education and activities to promote HPV vaccination to improve their knowledge on the subject.