This blog post is correct as of 26/01/2020.
At the end of December 2019, Chinese authorities alerted the World Health Organisation of a new pneumonia with an unknown cause in Wuhan, a large city in Central China. An investigation was then conducted to find out what was causing the pneumonia cases and by the 7th January, a new coronavirus, named novel Coronavirus (2019-nCoV) had been isolated from the patients in Wuhan.
Since then, cases have been reported in 14 other countries, including Korea, Thailand, Japan, the USA, Canada and France, and in multiple other provinces in mainland China. Currently, there are just over 2000 cases and 56 people have died.
Q: What is 2019-nCoV?
2019-nCoV, as it is called until a name can be decided upon, is a member of the coronavirus family of viruses. It is a large family of viruses that causes a variety of illnesses in mammals and birds. In humans, coronaviruses are often the cause of the common cold. However, also in the Coronavirus family are the viruses which caused SARS (Severe Acute Respiratory Syndrome) and MERS (Middle Eastern Respiratory Syndrome).
SARS caused a pandemic in 2002-3 of about 8000 cases and 800 deaths. It spread across the world from Guangdong in Southern China via Hong Kong, and no cases have been seen since. MERS has caused sporadic cases mostly in those with close contact with camels in Saudi Arabia, and it caused a small outbreak associated with hospitals in South Korea.
Q: So is it SARS? What about “Snake flu”?
No, it’s not SARS. nCoV is closely related to the virus that causes SARS, and is in a group with other “SARS-like” coronaviruses.
But it’s important to realise that they are different viruses, and represent separate spillovers from animals into humans. This also means they may have different clinical courses, including different transmissibility and fatality rates. However, the SARS virus gives us some good starting places for these rates until we have more information.
Some members of the UK press have also called it “Snake flu”. This is because a paper was published last week which suggested that animal that the virus usually lives in (the “animal reservoir” is a snake. This was based on science which has later been debunked, and most scientists think that the likely animal reservoir is a bat, like many other viruses. Furthermore, as discussed above, nCoV is not an influenza virus. So “Snake flu” manages to be wrong on both counts.
Q: What does it look like in patients? How does it spread?
nCoV gives symptoms of fever, dry cough and fatigue. This makes it hard to diagnose, as these symptoms are common to lots of illnesses.
Before these symptoms start, there appears to be quite a long “incubation period”. This is the period between infection and symptoms. The Chinese National Health Commission has said that patients are infectious in this incubation period, which makes this virus much harder to control, because individuals will be moving around normally and unintentionally exposing those around them.
This means infected people can get on a flight and move the virus across the world, or across the country, before they know that they’re unwell. This makes it harder to control than in an illness with a shorter incubation period, because people are more likely to travel in two weeks, rather than in two days.
It spreads between people through droplets, like flu and colds. This makes it quite hard to stop spreading, because usually diseases that spread like this don’t need much contact between people to catch the virus – ie you might be able to catch it from someone coughing on a bus, rather than having to be close for a long time. However, we don’t know this for sure about nCoV because there aren’t many clusters of human to human transmission investigated yet. There is confirmed human to human transmission though (unlike MERS).
Q. How deadly is it?
So far, the fatality rate is about 2%. It’s very difficult at this stage to confirm what the epidemic’s fatality rate will be. This is due to a number of reasons. First, we don’t know how much under-reporting there is. Because the symptoms are not specific to one illness, it’s difficult to pick up on in a doctor’s appointment, and it’s easy to misdiagnose, especially during ‘flu season. Secondly, early on in an outbreak, we tend to see the more severe cases because they’re easier to find and because they die faster – ie within three weeks. Thirdly, in lots of diseases, people that die tend to die faster than the recovery time in those that recover. So for people infected at the same time, we might have recorded deaths of those that have died, but not recoveries of those that have survived because we’ve only been looking for three weeks or so. All of these things may inflate the fatality rate beyond what it really is.
In terms of what we’re expecting to see? The fatality rate for SARS was about 11% overall, seasonal flu is less than 1%.
Q: Is it a pandemic?
There have been 26 cases reported in countries other than China, in nearby countries and in countries further afield, like the USA.
Until very recently, there was no evidence of human to human transmission outside of China. However, a case has been reported in Vietnam who does not have travel history to China, but is connected to a family member who does. The most likely explanation here is that there has been transmission in Vietnam, which is concerning.
Other than this, the cases are all from travellers coming from China. The definition of a pandemic is that there is human to human transmission across a wide region such as across multiple continents. So far, the epidemic is not a pandemic, even with this possible transmission in Vietnam.
Q: What is being done?
The Chinese public health and science authorities have moved very fast. Not only did they manage to detect a new respiratory virus during flu season (a very impressive feat), they have been very quick to analyse and share data with the global community.
It has taken a few weeks from detection to virus characterisation to genome sequences being released. Furthermore, it appears that the spillover from animals to humans occurred in early to mid-December, so the start of epidemic to detection window is very short. In comparison, it took three months for SARS to be reported internationally, and then another two months for the identification of the virus causing the epidemic.
In China, multiple cities, including Wuhan, have been put on travel lockdown. This means that flights and trains in and out of the cities have been suspended, as well as internal public transport. They have also fast-tracked the building of a new 1000 bed hospital to be completed next week to deal with the massive increase in demand for healthcare. Healthcare workers from all across China have been redeployed to Wuhan, including those who have experience with SARS from 2003.
There has been screening of patient’s temperatures on flights out of Wuhan, and many countries are screening flights that arrive from Wuhan on arrival. However, a detail of the case reported in Canada is worrying – they were symptomatic when they travelled. This means that the screening procedure is not completely effective, and so containment of the epidemic is less likely.
The World Health Organisation convened an Emergency Committee last week to discuss whether this outbreak constitutes a Public Health Emergency of International Concern (PHEIC). This is an announcement that the WHO can make to mobilise funding and the international community. However, they decided at this point that this epidemic is not a PHEIC. This was due to the lack of transmission in countries outside of China (at the time!), meaning that it was not yet an international emergency. This is not to say that it is not an emergency in China, and the WHO is still providing support to China and neighbouring countries to help in containing the virus. We don’t know yet whether the possible transmission in Vietnam will trigger another Emergency Committee meeting.
Q: How worried should we be?
It’s honestly difficult to tell. On the plus side, the response has been very fast and very strong. It appears from the outside that everything that should be being done, is being done. There is a decent amount of international cooperation and communication, and the scientific machinery is turning, with papers already being published about clinical aspects and modelling being done on the extent of the epidemic, and measure of transmission, such as R0.
On the downside, its long incubation period, non-specific symptoms and airborne transmission route make it hard to control. This is (probably) a virus which you can give to someone near you on a bus, one that you can carry across the world without realising. The likely start of the epidemic being in early to mid-December is positive because it was detected quickly, but negative because it means that there are over 2000 confirmed cases in just over a month.
So in conclusion, this is a scary new outbreak, but the response has been good so far. It is a very quickly evolving situation, with hundreds of new cases a day. The international community is watching carefully.
References:
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30185-9/fulltext
https://www.nature.com/articles/d41586-020-00191-5
Click to access 20200124-sitrep-4-2019-ncov.pdf
Image: The Yomiuri Shimbun via Reuters
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