Coronavirus – a breakdown

Image credit: Katie Chao and Ben Muessig via Flickr

2019-nCoV, a previously unknown type of coronavirus, emerged in the central Chinese city of Wuhan on December 31. Thousands of cases have been confirmed around China, with a few others scattered internationally.

What is 2019-nCoV?

Samples taken from patients exhibiting respiratory symptoms revealed a previously unknown virus within the coronavirus species, of the Coronaviridae family. Some of the most common culprits of the common cold are found within this family, as well as the Sars and MERS viruses responsible for epidemics in the 2000s. It is important to understand that virus families are large and varied, so until the novel strain is further characterised, no simplified comparisons should be drawn between these viruses. 

As of February 2, 14,557 cases and 304 deaths have been confirmed in China with a further 146 international cases across Asia, America, Europe and Australia. Experts from the University of Hong Kong estimated the actual number of cases to be much higher than those officially reported – their model of infection spread suggested 75,815 cases in Wuhan alone as of January 25. 

The early estimates point at a 2% mortality rate, with 15% of cases causing severe illness. As these numbers are based on officially confirmed cases, the real numbers are likely to be lower – there are thought to be many mild, or even symptomless cases, that go uninvestigated. The report from Hong Kong University would certainly suggest as such. If these cases were to be included in the numbers, the mortality and severity rates would be much lower. This is both a blessing and a curse; this virus seems to be much less dangerous than some of its relatives which is good news for those in risk areas. However, if these unreported or unknown cases are contagious too, the virus will be hard to contain. Many may have it unknowingly and not take the necessary precautions to prevent passing it on.

Although it is still too early to determine an accurate mortality rate, analysis suggests that this virus is not as dangerous as Sars or MERS – the majority of deaths have been in elderly, or chronically ill patients with conditions such as diabetes and Parkinson’s. Young and healthy individuals may be hospitalised in some cases, but infection is not generally a death sentence. To maintain some perspective, normal seasonal flu kills 290,000 to 650,000 people per year globally.

As of February 2, 14,557 cases and 304 deaths have been confirmed in China with a further 146 international cases across Asia, America, Europe and Australia.

There have been reports of patients being turned away without screening, or cases of coronavirus not being recorded in medical notes, which prompted concerns that China was trying to cover up the extent of the problem as they initially did in the Sars outbreak of 2002-3. However high up Chinese officials have since warned citizens and lower-level officials against covering up information about coronavirus, stating that they would be “nailed on a pillar of shame for eternity”.

How did it spread?

The first cases of 2019-nCoV were identified in Wuhan, the biggest city in central China and a national hub for trade and transportation. The source has been traced to a large seafood and wildlife market in the city where the virus made its jump from animals to humans. International cases are in people who had visited Wuhan within the last few weeks, or have had close contact with someone who has. With an incubation period of up to 2 weeks – longer than normal flu – many people could pick up the virus and travel elsewhere before later realising they were ill, explaining why cases are suddenly popping up in other Chinese cities.

The World Health Organisation (WHO) have stated that the virus has an animal source, with limited human-to-human transmission. This means that most people have contracted it directly from animals, and that catching it from another person is not easy. The few confirmed cases of human-to-human transmission are all within China, and between close family members or health professionals who have been working with the infected. It is currently unknown at what point an infected person becomes contagious – some viruses can be transmitted before the individual is aware of any illness, whereas others only become contagious after symptoms set in. Officials are hopeful that the low level of human-to-human transmission will make it easier to limit the spread.

What is being done about it?

A laboratory assay was quickly developed in a German research centre to facilitate fast and easy identification of the virus. Wuhan’s existing medical facilities are under enormous strain so an emergency 1000-bed hospital specifically to accommodate the growing number of cases is being built and could be ready as early as February 3rd.

WHO have stated that the virus has an animal source, with limited human-to-human transmission.

The goal in any epidemic is to limit the spread, but China faces an enormous challenge in this regard: the Lunar New Year holiday began on 25 January which traditionally sees hundreds of millions travelling into and around China. With families coming together in close contact and embarking on holidays both within China and abroad, not only will this aid the spread of the virus by human-to-human transmission, but it will render it very difficult to monitor the natural spread of the disease for characterisation purposes.

In a desperate attempt to reduce this, travel restrictions have been implemented across 10 cities, and the city of Wuhan is on lockdown. All public transport in and out of Wuhan, including flights, has been suspended, and although roads are not officially closed, there have been some reports of road blocks.

This is devastating timing for China where the Lunar New Year is of enormous cultural importance. These measures have been imposed to reduce movement but will not completely stop it. Total isolation of a city brings far too many challenges. The only way to prevent movement in or out would be to ring-fence the city with a military block, but if so, where would the border be drawn? As with all cities today, there is no clear edge – the city sprawls outwards into smaller towns and villages. Furthermore, there are already many cases outside the city, so isolating Wuhan would not lock up all sources of the virus.

Major tourist sites around China such as the Forbidden City in Beijing and a section of the Great Wall have also been closed and several major public events have been cancelled. 

To stop the unknowing spread of disease, many transport hubs in China and internationally, have started screening for coronavirus including Heathrow airport in London. This is not to deny entry but rather to ensure they seek the appropriate medical attention and do all they can to limit passing it on.

This is devastating timing for China where the Lunar New Year is of enormous cultural importance.

WHO did not immediately declare a global health emergency. The committee was divided, but it was decided that they would not designate it as a PHEIC (Public Health Emergency of International Concern) due to the limited number of cases outside of China and the low level of human-to-human transmission. They were clear that it was an emergency within China and that the case would be monitored continuously. A global emergency was declared a week later on January 30. In the decade 2009-19 there were five instances of PHEIC: swine flu, polio, Ebola, Zika virus and Kivu Ebola.

Where is it going?

The rapid spike in the number of cases over this week is alarming on the surface but misleading. It doesn’t mean hundreds of people contracted the virus overnight, but rather that screening and reporting of the infection is now far more efficient. Hospitals that were initially overwhelmed, have now got systems in place to deal with the massive numbers of incoming cases. Furthermore, the long and variable incubation period means that people likely contracted the virus steadily over the past few weeks and are only now showing symptoms. It is also easy to forget amongst the panic that it is currently flu season in many places, so fearful reports of respiratory symptoms may well be cases of other existing flu viruses – not necessarily coronavirus.

Caution is essential though. Epidemics are a given in any population – microbes will always exist. We can not know when these problems will arise, but what we can do is be prepared for them. Over time we have become better equipped for outbreaks. With constant improvements in technology and knowledge we can achieve faster containment, faster assays and faster treatments.

The 21st century does have a dark side however. Outbreaks today travel further and faster than they ever have before, thanks to the ease and speed of domestic and international travel. An unknowingly infected person can get on a plane and carry that microbe to the other side of the world within hours, meanwhile passing it on to all other passengers who can carry it to their own destinations. The swine flu pandemic of 2009 reached all continents in less than 9 weeks. In the midst of the MERS outbreak in 2015, it took just one traveller returning home from the Middle East to bring MERS to Korea triggering 200 cases and 36 deaths there.

In the decade 2009-19 there were five instances of PHEIC: swine flu, polio, Ebola, Zika virus and Kivu Ebola.

With WHO estimating that 70% of emerging human pathogens come from animals, the intensive farming of animals and extensive trade and transportation of them across borders also elicits great risk.

Contracted at an animal market and carried internationally within days, 2019-nCoV is a poster boy of modern day epidemics. But it is also the dream girl of modern day responses: a diagnostic tool was developed and ready for use two and a half weeks after WHO was first notified of a case, and an entire medical facility to treat patients is being built in even less.

For the average healthy person, and with modern medicine on our side, this virus is unlikely to be anything life-threatening. So why does it warrant so much attention? An epidemic is by definition the rapid increase of cases of an infection above the expected amount for a given population. It is these circumstances of the virus rather than the virus itself that are concerning. For the more vulnerable in the population – the elderly, the young, the chronically ill – a normal flu is dangerous but not a high day-to-day risk thanks to vaccinations and precautions to avoid being exposed. In an epidemic however, control is a huge challenge. This is a new strain which nobody is vaccinated against, and the increasing number of carriers make it unavoidable in high risk zones. 

Thankfully this virus has somewhat limited human-to-human transmission so with vigilance there is hope that the numbers will start to plateau after the initial rush of diagnoses are completed. It is likely that there will be more international cases confirmed – the UK reported its first cases last week, with two related people testing positive after travelling from Wuhan. Britons who were in Wuhan have been brought back to the UK and are currently under a two week quarantine.

As more official reports are released, epidemiologists will be able to better characterise the transmission patterns of the virus. Scientists are also working on identifying the specific animal source and potential other reservoirs of the virus, as well as a more precise incubation period. This information will be crucial in developing an in-depth action plan to tackle the spread of coronavirus. 

The message from WHO remains positive: they say China has a ‘stronger capacity’ to deal with infectious outbreaks than they did in the SARS epidemic. Stay tuned to WHO’s daily reports for further updates.

This article was written by Ailie McWhinnie and edited by Tara Wagner-Gamble.

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