February 10, 2020

expert reaction to report on the severity of the novel coronavirus, as posted on the MRC Centre for Global Infectious Disease Analysis website

A report, published on the MRC Centre for Global Infectious Disease Analysis website, reports on the severity of the novel coronavirus.

Dr Bharat Pankhania, of the University of Exeter Medical School, said:

“During an evolving outbreak, there will be many more people with mild symptoms, not requiring any medical intervention. These people will also be unlikely to go to their doctors. Thus, mild illness or illness with minimal symptoms, lack of doctors and lack of resources to go to the doctor could all add up to the true extent of the number of people infected being significantly higher than current estimates.  We need to try to gain a clearer idea of how the disease is spreading between people, in order to give a precise picture for the full range of the signs and symptoms following infection.

 “There is a concern around countries with underdeveloped healthcare systems.  With larger numbers of people infected, there will be considerable circulation of the virus and potential to infect many more people. These countries have poor health care facilities and minimal facilities for testing and centrally recoding data, which could mean a gross underestimate of the number of people infected.”

Prof Sheila Bird, Formerly Programme Leader, MRC Biostatistics Unit, University of Cambridge, said:

“The MRC Global Infectious Disease Analysis report is a key contribution – all the more impressive for the few actual data that the team could access. Critically few data were available on which to base onset-to-death distribution; and under-ascertainment of the level of infection. The latter, importantly, was based on infection prevalence detected in repatriation flights (to Japan and Germany, but not to UK which seemed to eschew testing) by assuming that infected individuals test positive for 14 days. The team also had access to observed onset, recovery and death times for 290 international travellers from mainland China up to 8th February 2020. Unfortunately, official case reports, in general, do not give dates of symptom onset nor death-date.

“As the data-sources that the research-team has access to enhance, the team’s estimated case-fatality rates will become more precise. Much more case-report detail is required (symptom onset-date, death-date or recovery-date). It would also be hugely insightful to see a detailed date-specific account of the contact networks for UK’s four index cases; and their testing.”

Prof Martin Hibberd, Professor of Emerging Infectious Disease, London School of Hygiene & Tropical Medicine (LSHTM), said:

“The new number crunching from the MRC Infectious Diseases group at Imperial has given some insights into the current case fatality rate estimates and shows how much these can vary at the moment (from 18% to 1%), with the numbers in general coming down over time, as more accurate estimates are made through the increased use of diagnostics in less severe cases. This is reminiscent of the 2009-nH1N1 Influenza strain, where initial estimates were also much higher than the now more established less than 0.1% rate overall. It is worth noting though, that despite this apparently low fatality rate for 2009-nH1N1, this pandemic caused serious additional problems (compared with typical seasonal Influenzas) to healthcare systems worldwide, showing why governments have placed such importance on this new coronavirus virus even as the case fatality rate drops.

“To improve our understanding of 2019-nCoronavirus (nCoV), new diagnostics are required, that will allow us to understand more about exposure and mild disease, including antibody detection assays to detect past exposure. While these are under rapid development, they may still be slower to be made available than for Influenza, where an established process was already in place for this well-known virus. With these tests in place, more systematic exposure studies can be conducted across populations, as well as more individual information about personal susceptibility following exposure.”

‘Report 4: Severity of 2019-novel coronavirus (nCoV)’ by Dorigatti et al. was posted on the MRC Centre for Global Infectious Disease Analysis website on Monday 10th February. This work is not peer-reviewed.

Declared interests

Prof Martin Hibberd:  “I have no conflicts with this work.”