Coronavirus more contagious than SARS and MERS, spread from 1 city to entire nation in 30 days, say experts
The new coronavirus, which has killed 2,118 and sickened 74,576 in mainland China, is more contagious than the related viruses which cause Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS).
This is according to a study by the China Centers for Disease Control and Prevention (CDC), which analyzed 72,314 patient records. This includes 44,672 (61.8%) confirmed cases, 16,186 (22.4%) suspected cases, 10,567 (14.6%) clinically diagnosed cases (Hubei Province only) and 889 asymptomatic cases (1.2%).
“A main finding of this characterization and exploratory analysis of the first 72,314 cases of COVID-19 found in China in the 40 days between first recognition of the outbreak of pneumonia with unknown etiology on December 31, 2019, to the end of the study period on February 11, 2020, is that this novel coronavirus is highly contagious,” says the paper published by the China CDC.
It says: “The virus is distinct from both SARS-CoV and MERS-CoV, yet closely related. Early cases suggested that COVID-19 (that is, the new name for disease caused by the novel coronavirus) may be less severe than SARS and MERS. However, illness onset among rapidly increasing numbers of people and mounting evidence of human-to-human transmission suggests that 2019-nCoV is more contagious than both SARS-CoV and MERS-CoV.”
In particular, say experts, the analysis chronicles the extremely rapid spread of the novel coronavirus despite extreme efforts to contain it. The researchers explain that the infection has spread very fast -- from a single city to the entire country within only about 30 days.
“It has achieved such far-reaching effects even in the face of extreme response measures, including the complete shutdown and isolation of whole cities, cancellation of Chinese New Year celebrations, prohibition of attendance at school and work, massive mobilization of health and public health personnel as well as military medical units, and rapid construction of entire hospitals,” says the team.
With every disease outbreak, scientists try to figure out its intensity by using the reproduction number or RO.
“The formal definition of a disease’s R0 is the number of cases, on average, an infected person will cause during their infectious period. R0 estimates have been an important part of characterizing pandemics or large publicized outbreaks, including the 2003 SARS pandemic, the 2009 H1N1 Influenza pandemic and the 2014 Ebola epidemic in West Africa,” writes Joseph Eisenberg, Professor and Chair of Epidemiology, University of Michigan, in The Conversation.
In the case of COVID-19, while there have been some estimates, a final number is yet to be determined.
“The Imperial College group has estimated R0 to be somewhere between 1.5 and 3.5. Scientists from the Chinese Academy of Sciences Institute of Automation and the University of Chinese Academy of Sciences have estimated the R0 to be much higher, at 4.08. These differences are not surprising; there’s uncertainty about many of the factors that go into estimating R0, such as in estimating the number of cases, especially early on in an outbreak,” explains Eisenberg.
The fatality rate of COVID-19, however, is less than SARS or MERS. Of the 44,672 confirmed cases, a total of 1,023 deaths had occurred till February 11, 2020, leading to an overall case fatality rate of 2.3%, shows analysis. By comparison, SARS had a mortality rate of 9.6% during the 2003 outbreak, while MERS has a case fatality of 34.4%.
“In light of this rapid spread, it is fortunate that COVID-19 has been mild for 81% of patients and has a very low overall case fatality rate of 2.3%,” say researchers.
However, despite the lower case fatality rate, COVID-19 has, so far, resulted in more deaths than SARS and MERS combined.
Globally, the total number of people infected with SARS was over 8,400 and there were 916 deaths, according to the World Health Organization (WHO) estimates.
At the end of December 2019, a total of 2,502 laboratory-confirmed cases of MERS, including 861 associated deaths (case–fatality rate: 34.4%) were reported globally, says WHO.
On February 19, China's National Health Commission said that the country’s daily number of newly recovered novel coronavirus patients has surpassed that of new confirmed infections for the first time.
“Tuesday saw 1,824 people walk out of hospital after recovery, higher than the same day's number of new confirmed infections of the novel coronavirus, which was 1,749,” said the Commission.
The latest estimates on Thursday, February 20, show that new virus cases in China rose by over 390 from the previous day. This is a considerable drop from the 1,749 new cases recorded on February 19.
However, the situation remains severe in Hubei province and its capital, Wuhan, where the new coronavirus was first detected in December. More than 80% of the country's cases are in Hubei and 95% of the deaths, according to data from the National Health Commission.
The experts of the current study also warn that despite efforts, China might face more challenges. “Huge numbers of people will soon be returning to work and school after the extended New Year holiday. We need to prepare for a possible rebound of the COVID-19 epidemic in the coming weeks and months,” says the team.