2.23 的報導，2.29發布
新冠病毒COVID-19在2019年年底在武漢出現後，現已擴散到中國大陸以外的29個地區和國家，超過1000人被確診感染。倫敦帝國理工學院發布報告通過航空流量和一些國家對病毒的檢測敏感度分析中國流向全球的新冠疫情。
該報告根據武漢天河國際機場的航空流量和國際檢測到的病例等數據，分析從中國大陸輸出到世界不同地區的新冠病毒病例，比較特定國家地區不同的確診比例和空運量得出結論稱，儘管武漢和中國其他城市對旅行的嚴格限制，減少了往返中國的旅客絕對數量，但是我們仍然估計，在全球範圍內，從中國流出的大約三分之二的新冠COVID-19病例尚未被檢測到，可能導致在中國大陸以外，多條人與人之間傳染的鏈條還沒有被發現。毫無疑問，這些症狀的嚴重性會因輸出的病例而不同，一些病例要比另一些更難檢測到。
該報告追踪武漢天河國際機場國際航班的痕跡，用新加坡做參照，評估每個國家/地區對疫情監視的敏感度。其中芬蘭，尼泊爾，比利時，瑞典，印度，斯里蘭卡和加拿大的監視新冠病毒敏感度評估都高於新加坡。也就是說，這些國家在每個航班中發現的病例要高於新加坡。
該報告表示，在多個案例中，一些地區和國家預計的新冠病例明顯高於已查出病例。但是除了用監視病毒敏感性做基準的新加坡和上面列出的國家以外，我們有意未確定其他的特定國家。
該報告介紹了做出上述評估所使用的參考依據和計算公式。包括從航空旅行協會（IATA）獲得的武漢天河國際機場2016年1-3月的航班數據。
Report claims two-thirds of global coronavirus cases have gone undetected
A new report from a WHO infectious disease modeling team based at Imperial College London is estimating about two-thirds of Covid-19 cases worldwide have gone undetected. The analysis suggests the global spread of the novel coronavirus is significantly greater than the current volume of confirmed cases.
“We are starting to see more cases reported from countries and regions outside mainland China with no known travel history or link to Wuhan City,”
explains Natsuko Imai, one of the authors on the new report. “Our analysis, which extends and confirms previously released analysis by other groups using flight volumes from Wuhan City and the reported number of COVID-19 cases, demonstrates the importance of surveillance and case detection if countries are to successfully contain the epidemic.”
As of February 23, 2020, there are
over 78,000 confirmed cases of Covid-19, the vast majority of which are concentrated in China.
Prior studies have suggested most cases present with mild symptoms. Only a small minority of confirmed cases seem to progress into serious pneumonia-like disease, leading some researchers to suggest the virus may have spread wider than current numbers indicate.
This new report set out to explore how accurate current country-based surveillance of the disease may be, in relation to the average volume of travelers flying out of the epidemic epicenter in Wuhan, China.
“We compared the average monthly number of passengers traveling from Wuhan to major international destinations with the number of COVID-19 cases that have been detected overseas,”
says another author on the new report, Sangeeta Bhatia. “Based on these data, we then estimate the number of cases that are undetected globally and find that approximately two thirds of the cases might be undetected at this point. Our findings confirm similar analyses carried out by other groups.”
The report concludes it is very likely a number of undetected chains of transmission have begun in many countries across the globe. Director-General of the World Health Organization Tedros Adhanom Ghebreyesus affirmed this growing concern during a recent WHO briefing.
"Although the total number of Covid-19 cases outside China remains relatively small, we are concerned about the number of cases with no clear epidemiological link, such as travel history to China or contact with a confirmed case,"
said the Director-General in the February 22nd briefing.
Although the Director-General
did state the “window of opportunity for containing this coronavirus is narrowing”, the WHO has not yet classified this outbreak as a pandemic. Less than 2,000 cases have been currently confirmed outside of China, however, as this new report indicates, the viral spread may be broader than the official numbers suggest.
Jennifer Nuzzo, an epidemiologist from Johns Hopkins University,
said last week the spread of the virus already constitutes a global pandemic, despite the WHO’s reluctance to deem it so officially. While the difference between an epidemic and a pandemic may be a somewhat semantic one, based on geographic spread of the disease, Nuzzo suggests the terminology does fundamentally affect how we deal with the virus on a local level.
"I am of the belief ... that we are in the early stages of a pandemic,"
said Nuzzo. “I think it's important for us to ... talk openly about whether containment of an epidemic is possible, or whether we are exacerbating pandemic spread, because my worry is we're diverting resources from the community level.”
Source:
Imperial College London
