How deadly and how contagious is the coronavirus? When do symptoms appear, and can the patient spread the virus before symptoms appear? The experts are focused on these and other questions, but there are no clear answers yet.
- How contagious is the coronavirus?
- When does an infected person start spreading the virus?
- Person-to-person transmission.
- What are the symptoms of coronavirus?
- The incubation period of the coronavirus.
- How to avoid infection?
So the facts.
As of Thursday, about 7,780 cases have been confirmed in China, the country of origin of the virus, resulting in at least 170 deaths. Virus distribution map.
The virus has spread from Wuhan city throughout China to more than 15 countries, with about 60 of them in Asia, Europe, North America and, more recently, the virus has appeared in the Middle East.
Outside of China, not a single death from the coronavirus has been recorded.
2019- nCoV, as it was named, is part of the coronavirus family, the source of two previous deadly epidemics.
An outbreak of SARS in 2002/03 (Severe Acute Respiratory Syndrome) began in Guangdong province and killed 774 out of a total of 8,096 infected. The 2012 MERS (Middle East Respiratory Syndrome) outbreak killed 858 out of 2,494 people infected.
The corresponding mortality rates for SARS and MERS patients were 9.5 and 34.5 percent, much higher than for the new coronavirus, which, according to French Health Minister Agnes Buzin, is “less than five percent.”
Experts say this figure is likely to decline as the ratio of deaths to reported cases continues to rise.
The coronavirus is “less deadly than SARS or MERS, but more infectious,” Buzin said at a news conference on Tuesday.
According to the World Health Organization (WHO), seasonal flu kills between 290,000 and 650,000 people a year. In the United States, the death rate among people infected with the flu is about 0.13 percent, the Centers for Disease Control estimates.
How contagious is the coronavirus?
Estimates of how easily the coronavirus spreads from a 'base rate of reproduction' of 1.4 to 3.8 people infected by a single patient, David Fisman, a professor at the University of Toronto, estimates.
Chinese scientists, however, say that one patient will, on average, infect 5.5 other people.
“If it turns out to be accurate, it will partly explain the surprisingly rapid increase in the number of cases in Hubei province and beyond, and suggests that China is facing a very difficult road,” said Stephen Morrison of the Center for Strategic and International Studies in Washington.
British Imperial College scientists estimate that every coronavirus patient infects an average of 2.6 people, making it about as infectious as annual flu outbreaks.
When does an infected person start spreading the virus?
This important question remains unanswered.
Ma Xiaowei, head of China's National Health Commission, said the coronavirus could be transmitted before symptoms appear, during the incubation period of the disease.
This is also true for seasonal flu, but not for SARS.
According to some experts, this remains a working hypothesis and has yet to be confirmed.
“In my opinion, it is premature to conclude from the available evidence that a new virus can be transmitted before symptoms appear,” said Mark Woolhouse, professor of infectious disease epidemiology at the University of Edinburgh.
“In the absence of any cure or vaccine, our main hope in fighting the epidemic is to quickly detect cases and immediately prevent further transmission through patient isolation,” he added.
“The effectiveness of these interventions would be compromised if transmission took place before symptoms appeared and the patient went to a health facility.”
Person-to-person transmission.
The virus is believed to have originated from wild animals, probably bats, but is now spreading from person to person.
Almost all cases of such transmission have occurred in China, but there have also been a few cases in Vietnam.
“There have been only a few isolated cases of primary transmission worldwide,” Morrison said. “The risk remains very low for the United States and other advanced economies.”
But this situation may be different in other parts of the world.
“If the virus spreads to countries in Africa and other countries where health security is limited, there could be serious secondary outbreaks outside of China,” Morrison added.
What are the symptoms of coronavirus?
Chinese scientists told The Lancet Friday that, based on a study of 41 previously identified cases, some of the symptoms of the new virus resemble those of SARS.
All patients had pneumonia, most had a fever, three quarters of them coughed and more than half had breathing problems.
However, there are some 'important differences,' said lead author Bing Lao.
Identifying the symptoms of the coronavirus is even more important – and difficult – due to the simultaneous seasonal flu epidemic that has similar symptoms.
The incubation period of the coronavirus.
On Monday, WHO estimated an incubation period of two to ten days. Among 34 patients examined by researchers from the Netherlands, the median period was 5.8 days.
According to a letter published in the New England Journal of Medicine, a 27-year-old Vietnam man infected by his father who was in Wuhan developed symptoms three days later.
As a precautionary measure, the health authorities in France and other countries have established a isolation period of 14 days for repatriated citizens and others arriving from the hot zone of the spread of coronavirus.
How to avoid infection?
Health authorities and scientists say standard precautions against viral diseases apply: wash your hands often, try to avoid crowds, and avoid touching your face.
Anyone who gets the coronavirus should be isolated!
“Given that a significant number of SARS and MERS patients have been infected in healthcare facilities,” precautions must be taken to prevent this from happening again, Chinese scientists warned in The Lancet.
Sources: Agence France-Presse
