https://www.cpr.cuhk.edu.hk/sc/press/cu-medicine-estimates-20000-covid-19-hidden-infections-in-hong-kong-all-vaccinated-persons-in-hk-developed-neutralising-antibody-after-two-doses-urgent-call-for-the-largely-unprotected-population-t/
中大醫學院推算全港約有二萬名未被發現新冠感染者