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Coronavirus Infections May Be Going Undetected

4 years, 4 months ago

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Posted on Feb 24, 2020, 8 p.m.

A new study from Imperial College London researchers based at the W.H.O Collaborating Centre for Infectious Disease Analysis, and J-IDEA-Abdul Latif Jameel Institute for Disease and Emergency Analytics suggests that nearly two thirds of new cases of COVID-19 have gone undetected. 

Sangeeta Bhatia, author of the 6th report explained in a statement that, “We compared the average monthly number of passengers traveling from [outbreak epicenter] Wuhan to major international destinations with the number of COVID-19 cases that have been detected overseas. 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.

Previous research has shown that only a small subsection of confirmed cases display serious symptoms such as pneumonia, and globally researchers are working to understand how the virus spreads as well as determine why/if the virus can be transmitted by those who are not displaying any symptoms. Based on the numbers released by China the total fatality rate is fairly low, but this could change especially if the virus mutates, and there is speculation of the figures provided being seriously downplayed. 

Globally there are over 78,000 confirmed reported cases, with new cases in Africa, Italy, South Korea, America, Iran, Asia, and China causing the reported number of causes and deaths to spike over the last few days. Financially even the global market is feeling the effects of the coronavirus leading to worries from investors regarding a global economic slowdown. The Chinese economy is suggested to have already taken as much as a $60 billion loss, and if the fallout from the virus can’t be contained it could cost the Chinese economy as much as a staggering $6 trillion. What is worse is that this could spiral outwards, as much of the world has come to rely on China, resulting in a global recession that many markets will not be able to weather. 

With the continued widespread of the virus outside of China has some scientists worried, “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,” noted co-author Natsuko Imai in the statement. Hence why their report “demonstrates the importance of surveillance and case detection if countries are to successfully contain the epidemic.”

Cases vary in severity of symptoms, making some cases harder to detect than others, and some countries have reported detecting significantly fewer cases than would be expected based on the volume of flight passengers arriving from affected cities, especially that of the epicenter Wuhan City, China. 

Gina Cuomo-Dannenburg, report author, added: “We compiled data from a variety of publicly available sources, such as national and provincial ministries of health and local news, to determine information about travel history, exposure and symptom onset of individual patients observed outside of mainland China. We would like to thank countries for their continued transparency in presenting information on new cases, and would like to encourage communication of patient outcomes going forward to present a true picture of severity and clinical presentation.”

63% of cases are estimated to be undetected based on comparisons with Singapore only; when comparing with Singapore, Finland, Nepal, Belgium, Sweden, India, Sri Lanka and Canada 73% of cases of COVID-19 are estimated to be undetected. 

Professor Christl Donnelly, report author, explained: “We were able to analyse data collected around the world to determine how individual countries compared to those who have reported and confirmed the high numbers of cases compared to their connectedness with Wuhan city (as judged by the average number of international passengers per month).  Bringing these numbers together we have estimated that worldwide two thirds of COVID-19 cases exported from mainland China have not been picked up by surveillance programmes.”

Professor Neil Ferguson, report author, added:“Countries around the world have been focused on containing the international spread of COVID-19 by detecting cases in travellers from China. However, surveillance approaches and capabilities have varied between countries. The resulting variation in the numbers of cases detected in each allows us to assess what proportion of cases in travellers may have been detected overall, by comparing case numbers in the countries with the highest detection rates with those in other countries. In agreement with the results from similar studies, we conclude that approximately two-thirds of cases in travellers from China have not yet been detected. It is highly likely that some of these undetected cases will have started chains of transmission within the countries they entered.”

In separate research with findings published in the Lancet suggest that 61.5% of coronavirus patients with severe pneumonia will not survive; patients especially vulnerable to severe COVID-19 infection which includes the old, young and those with existing conditions are more likely to die at a higher rate than they did from SARS and MERS.

This study of 52 critically ill adults of 710 at Wuhan Jin Yin-tan hospital has found that 61.5% of affected patients that required hospitalization and intensive monitoring succumbed to the virus to become “non-survivors.” Based on their findings the researchers concluded that COVD-19/ SARS-CoV-2 is more lethal for vulnerable patients than patients of MERS or SARS were; findings are presented in a series of tables breaking down each patient’s symptoms and path to recovery/death. The 52 patients had a mean age of 59.7 years old, 35 were men of which 40% had been diagnosed with some kind of chronic illness, 98% were found to have a fever, and 61.5% died by 28 days.

“Like SARS-CoV and Middle Eastern respiratory syndrome (MERS)-CoV, SARS-CoV-2 is a coronavirus that can be transmitted to humans, and these viruses are all related to high mortality in critically ill patients.12 However, the mortality rate in patients with SARS-CoV-2 infection in our cohort is higher than that previously seen in critically ill patients with SARS. In a cohort of 38 critically ill patients with SARS from 13 hospitals in Canada, 29 (76%) patients required mechanical ventilation, 13 (43%) patients had died at 28 days, and six (16%) patients remained on mechanical ventilation. 17 (38%) of 45 patients and 14 (26%) of 54 patients who were critically ill with SARS infection were also reported to have died at 28 days in a Singapore cohort13 and a Hong Kong cohort,14 respectively. The mortality rate in our cohort is likely to be higher than that seen in critically ill patients with MERS infection. In a cohort of 12 patients with MERS from two hospitals in Saudi Arabia, seven (58%) patients had died at 90 days.15 Since the follow-up time is shorter in our cohort, we postulate that the mortality rate would be higher after 28 days than that seen in patients with MERS-CoV.”

UPDATESwitzerland, Austria, Croatia and Spain confirm first coronavirus cases: Two cases have been reported in Austria’s Tyrol state, one case in the Croatian capital of Zagreb, one in mainland Spain’s Catalonia region and one in Switzerland’s Ticino region, likely affecting European stock markets which closed around 2% lower on Tuesday; Italy continues to be the most affected country in Europe. 

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