嚴重急性呼吸道症候群 (SARS)疫情於2003年爆發,導致8,000病例800人因病死亡,最終在相關嚴密防疫措施下告一段落。然而,自2019年12月底新冠肺炎疫情爆發以來,截至2020年2月28日,新型冠狀病毒(COVID-19)疫情,已經造成全球82,000病例,2,800人因病死亡。SARS和新型冠狀病毒有相當程度的相似性,但也有一定程度的差異,要能成功防疫不讓新冠肺炎疫情擴大,幾下幾點是關鍵:1. SARS和新型冠狀病毒的基因體及傳播途徑有高度相似性。2. SARS最後有效的絕跡,取決於從中央政府到基層大規模嚴密阻絕人傳人的傳播。 3.傳統公共衛生的防疫措施,例如: 隔離、檢疫以及避免近距離接觸,能有效抑制SARS病毒傳播。但這些防疫措施是否對新型冠狀病毒有效,主要關鍵在於兩者的相異性。4.目前已知新型冠狀病毒傳播力比SARS病毒強,感染新型冠狀病毒病例症狀比SARS輕微,可能造成防疫漏洞。5.因為大規模的社區傳播, 可能使得人傳人的傳播途徑,無法有效控制;因此,政府若無法將疫情控制住,至少要能做到將發生新冠肺炎的高峰期及死亡案例降低。

(財團法人國家衛生研究院 蔡慧如博士摘要整理)

Summary

The severe acute respiratory syndrome (SARS) outbreak in 2003 resulted in more than 8000 cases and 800 deaths. SARS was eventually contained by means of syndromic surveillance, prompt isolation of patients, strict enforcement of quarantine of all contacts, and in some areas top-down enforcement of community quarantine. By interrupting all human-to-human transmission, SARS was effectively eradicated. By contrast, by Feb 28, 2020, within a matter of 2 months since the beginning of the outbreak of coronavirus disease 2019 (COVID-19), more than 82 000 confirmed cases of COVID-19 have been reported with more than 2800 deaths. Although there are striking similarities between SARS and COVID-19, the differences in the virus characteristics will ultimately determine whether the same measures for SARS will also be successful for COVID-19. COVID-19 differs from SARS in terms of infectious period, transmissibility, clinical severity, and extent of community spread. Even if traditional public health measures are not able to fully contain the outbreak of COVID-19, they will still be effective in reducing peak incidence and global deaths. Exportations to other countries need not result in rapid large-scale outbreaks, if countries have the political will to rapidly implement countermeasures.

Introduction

In November, 2002, the severe acute respiratory syndrome coronavirus (SARS-CoV) emerged in China causing global anxiety as the outbreak rapidly spread, and by July, 2003, had resulted in over 8000 cases in 26 countries. In December, 2019, a novel coronavirus, named SARS-CoV-2, emerged in Wuhan, China, and led to a rapidly spreading outbreak of coronavirus disease 2019 (COVID-19). By Jan 30, 2020, COVID-19 was declared a public health emergency of international concern. The similarities between SARS-CoV and SARS-CoV-2 are striking, not only in name. The whole genome of SARS-CoV-2 has a 86% similarity with SARS-CoV.1 Both viruses share high degrees of homology to SARS-like coronaviruses isolated in bats, suggesting that bats are the probable origin of both SARS-CoV and SARS-CoV-2. Live animal markets selling multiple species of wild and domestic animals in proximity to large populations of densely housed humans are thought to be the source of both outbreaks. Even in terms of disease dynamics there are apparent similarities. The main transmission route is thought to be respiratory droplets, although viral shedding via faeces has also been reported for both viruses. The angiotensin-converting enzyme 2 (ACE2), found in the lower respiratory tract of humans, has been identified as the receptor used for cell entry for both SARS-CoV and SARS-CoV-2.23 COVID-19 and SARS have a median incubation time of about 5 days. The mean serial interval of COVID-19 is 7·5 days (95% CI 5·3–19·0) and the initial estimate for the basic number (R0) was 2·2 (95% CI 1·4–3·9),4 similar to that reported for SARS (mean serial interval 8·4 days, and basic R0 range 2·2–3·6 for serial intervals of 8–12 days).5 Risk factors for severe disease outcomes are old age and comorbidities. The progression for patients with severe disease follows a similar pattern in both viruses, with progression to acute respiratory distress syndrome approximately 8–20 days after onset of first symptoms, whereby lung abnormalities on chest CT show greatest severity approximately 10 days after initial onset of symptoms.6789

Author:Annelies Wilder-Smith, Calvin J Chiew, Vernon J Lee, et al.
原文連結:https://www.sciencedirect.com/science/article/pii/S1473309920301298?via%3Dihub

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