Time lags, delays, and problems in reporting may mean that the scale of the deadly new coronavirus outbreak is far worse than current official figures make out.
According to a new study in the journal The Lancet, over 75,000 people may have been infected with coronavirus in the city of Wuhan alone – as of January 25, the most recent data used in the study – almost 10 times more than the official number of confirmed reported cases at the time, and more than quadruple the total cases reported in mainland China today. The findings suggest that each infected person could spread the virus to two or three individuals on average, resulting in an epidemic that doubled in size every 6.4 days.
While the researchers don’t suggest any sinister motive behind the discrepancy between their figures and official figures, they say it does highlight the need for authorities worldwide to prepare and establish protocols for the outbreak before it comes knocking at their door.
"Not everyone who is infected with 2019-nCoV would require or seek medical attention," Professor Gabriel Leung, senior study author from the University of Hong Kong, said in a statement.
"The apparent discrepancy between our modeled estimates of 2019-nCoV infections and the actual number of confirmed cases in Wuhan could also be due to several other factors," he added. “These include that there is a time lag between infection and symptom onset, delays in infected persons coming to medical attention, and time taken to confirm cases by laboratory testing, which could all affect overall recording and reporting."
This figure was reached using a mathematical model that looked at the number of confirmed 2019-nCov cases, then combines it with data on domestic and international travel. They also used information about how fast severe acute respiratory syndrome (SARS), another member of the coronavirus family, travels to estimate rates of transmission from person to person.
The outbreak of 2019-nCov started in the Chinese city of Wuhan in December 2019, and has now caused more deaths than the infamous SARS outbreak of 2002-2003. It affects the respiratory system, causing pneumonia-like symptoms, such as fever, breathing difficulties, a cough, and shortness of breath. It spreads through close contact with infected people, primarily via coughs and sneezes that release germ-carrying air droplets within a range of about an arm span.
The researchers warn that their study does have some limitations to be considered. It’s still relatively early days for the outbreak, so many aspects of the novel virus remain unknown. Although it makes sense to compare the outbreak to the SARS epidemic, we still know where exactly the similarities begin and end. 2019-nCoV is part of the coronavirus family, however, another new study found that it was genetically distinct from both SARS and the Middle East respiratory syndrome (MERS). As such, the figures should be taken as informed estimates, not concrete facts.
"The model suggests that there have been tens of thousands of cases in Wuhan already, which is in line with estimates made by other groups,” Professor John Edmunds, an independent expert from the Centre for the Mathematical Modelling of Infectious Diseases at London School of Hygiene & Tropical Medicine, commented on the study.
“The forward projections are much more speculative, however, and are probably best viewed as indicative rather than hard forecasts,” Dr Edmunds added. “This is inevitable, as at such an early stage in an epidemic when there is so little information on the virus and how it spreads, it is very difficult to make accurate predictions.”