新冠完結,全球復常。但新冠病毒並非最後一場大流行,新發傳染病定必陸續有來。為未來的大流行作準備,必須有高質科研、足夠的基礎建設、迅速應變計劃及措施,完善公營醫療機構、公共衛生及流行病學監察系統,時刻與國際組織保持聯繫溝通等,缺一不可。香港大學將聯同各地學者(包括內地、美國、澳洲及新加坡等),成立大流行科研聯盟(Pandemic Research Alliance),藉此共同尋找具潛力病源,追蹤新發傳染病,應對未來大流行。行政長官於上星期向立法會發表《2023年施政報告》,認為香港必須加強抗擊傳染病能力,但如何用有限度資源去達到監測、預警和防控卻是一門學問。本文綜合本團隊早前於醫學期刊發表之醫學評論文章,從而討論流行病學監察系統(註1)。
頻繁的基因突變會導致抗原漂移(antigenic drift)及分段基因重組(gene reassortment),即俗稱的病毒基因洗牌。此變異使抗原出現轉移,令病毒能重新感染具免疫力的群體,甚至適應不同的宿主細胞環境,從而出現跨物種傳播(cross species transmission),例如2009年豬流感H1N1病毒,以及H5N1和H7N9等禽流感病毒(註7至9)。除人類冠狀病毒OC43和HKU1可能起源於囓齒類動物外,其餘人類冠狀病毒,包括229E、NL63、MERS-CoV、SARS-CoV-1和SARS-CoV-2均被認為是從蝙蝠透過中間宿主傳播到人類(註10)。
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