1. Centre for Health Protection. The collection of measles news press release in March and April of 2019, the Centre for Health Protection (CHP) official website, the Government of the Hong Kong; 2019. Available from: https://www.chp.gov.hk/en/miniweb/press_release/100020.html. Accessed May 27, 2020.

2. Centre for Health Protection. The summary report of individual measles cases in Hong Kong in the first half of 2019, the Centre for Health Protection of Hong Kong; 2020. Available from: https://www.chp.gov.hk/files/pdf/daily_update_on_measles_cases_in_2019_eng.pdf. Accessed May 27, 2020.

3. Centre for Health Protection. The number of notifiable infectious diseases by month in Hong Kong, the statistics on communicable diseases, the Centre for Health Protection (CHP), the Government of the Hong Kong; 2019. Available from: https://www.chp.gov.hk/en/static/24012.html.

4. Fact sheets of the Hong Kong International Airport (HKIA), the HKIA official website; 2019. Available from: https://www.hongkongairport.com/iwov-resources/file/the-airport/hkia-at-a-glance/facts-figures/HKIA_FactSheet_181220_EN.pdf. Accessed May 27, 2020.

5. Measles fact sheet, World Health Organization (WHO). 2019. Available from: https://www.who.int/immunization/diseases/measles/en/.