Monday, 3 February 2020

Should I Worry About Covid-19, the Wuhan 2019 nCoV Coronavirus?

Photo: CDC/C.S. Goldsmith - https://www.cdc.gov/sars/lab/images.html

Updated 16 February 2020

What is the COVID-19 coronavirus?


Includes charts of epidemic cases and deaths

COVID-19, formerly the Wuhan 2019 nCoV, is the WHO (World Health Organisation) name for the 2019 novel Coronavirus. This is a new coronavirus that began in the Chinese city of Wuhan. It causes a viral pneumonia. Symptoms can include fever, sore throat, dry cough, fatigue and breathing difficulties. There are lots of different coronaviruses infecting humans and animals. Some of the colds you had in the past were probably caused by a human coronavirus. This Covid-19 appears to be mild in most cases. However, those with pre-existing health problems, the very young and the elderly are more likely to be severely affected.  See below for more information. 

COVID-19 seems to be at least as infectious as flu, with an average rate of one person infecting between 1.4 to 4 people, with suggestions tending towards the higher figure. One person with Rubella infects 5 to 7 people and with measles, 12 - 18 people.

On 16th February, 2020, more than 69267 people have been infected, the vast majority of them in China. As many people only have very mild symptoms and might slip through unnoticed, there is speculation that the figure could be considerably higher. Only 9 cases have been detected in the UK. There have been more than 1666 deaths in China, 4 deaths outside of China.

The charts below appear to indicate  that the number of new cases in China is tailing off and the number of deaths is also slowing down, in that they have stopped increasing exponentially (ever faster) and are almost linear over the past week. In the rest of the world, cases are still increasing exponentially but the numbers, spread over so many countries, are low and hopefully manageable.

Current estimates are that the death rate is likely to be 2%, or 1 in 50. For comparison, Measles kills 1 in 500, a previous coronavirus – SARS - killed  almost 1 in 10. There were 80,000 Seasonal influenza and pneumonia deaths during the particularly bad 2018 season in the US, On average there are about 8,000 flu deaths per year on average in England.

If you are fit and healthy, the COVID-19 disease is much less likely to be severe. You are at much greater risk if you have a compromised immune system or are affected by other illnesses. As with many diseases, the very young (under fives) or over 65s are vulnerable.

Recent WHO figures from their situation reports are:

Figure 2. Chart of progress of COVID-19 epidemic. Using data from WHO Situation Reports. Note that China changed its assessment method from laboratory tests to clinical cases (green triangle). For 5 days in January, WHO also gave values for predicted cases (red squares) which might seem to lead up naturally to the clinical case number in China today. WHO still including laboratory confirmed cases (blue squares).

Figure 3. COVID-19 cases in rest of world

Figure 3. COVID-19 deaths in China

Table of progress of COVID-19 epidemic. Using data from WHO Situation Reports and also numbers from new Chinese clinical assessment method of counting cases.

Will I be infected?

Initial information was that you have to be within 2 meters of someone having the illness for at least 15 minutes to breathe in enough virus to cause an infection. More recent cases suggest it may infect more easily. Touching surfaces contaminated by the virus and then touching your mouth or eyes can also transfer the virus. This does not mean that you will always become ill (see How can I protect myself below).

The virus is shed into the air by an infected person. The idea that virus is spread even people are not displaying obvious symptoms like fever or a runny nose seems to be less likely.

The virus is unstable outside of the body and is thought to be inactive after 24 hours.
Your risk of infection is dramatically reduced the further away you are from ill people.

What does the virus COVID-19 do?

The COVID-19 coronavirus infects the cells lining the airways of the body, the epithelial cells. In severe cases it seems to progress to the lungs, causing pneumonia.

The virus consists of a complex protein capsule that contains the virus genes. The virus genes are on a single strand of RNA – not DNA. This strand is 29903 bases (units) long. At least seven isolates of the virus have been sequenced and their sequences made publically available for all scientists - see https://www.ebi.ac.uk/ena/browser/text-search?query=Wuhan%202019%20nCoV.

On contact with one of your epithelial cells, some of the proteins, probably the spike protein, on the outside of the capsule interact with proteins on the surface of your cell. The cell is triggered to take up the virus. Inside the cell, the virus hijacks your cell’s own functions to make copies of its single RNA strand. The genes encoded on the virus RNA are also translated into a range of virus proteins. New virus particles are then assembled and then either are exported by the cell or released when the cell dies. Neighbouring cells are then infected and, if the conditions are right, the virus begins to spread along your airways.

The symptoms you may get range from fever, sore throat, dry cough, fatigue and breathing difficulties. They are in part due to the virus affecting/killing cells but also due to your body going into overdrive to try to fight the virus infection. How ill you are is a balance between virus multiplication and how fast and effectively your body defence is successful. There is more information below in the next section, on how you can protect yourself.

How can I protect myself?

There is no vaccine for COVD-19 yet – but with the full sequence of the virus available, work is in progress to provide a vaccine in the next months. Therefore isolation and quarantine remain the most effective means to prevent the spread of the disease. Things you can do are:

  • Keeping healthy by eating and sleeping well, exercising
  • Avoiding locations and people with the illness
  • Hand-washing
  • Use of hand sanitisers
  • Good personal hygiene generally

Keeping healthy is a great prophylactic as it means that your immune system is in best condition. Our bodies are actually geared to be alert to any foreign invaders and illnesses and the incoming virus does not have it all its own way.

In their paper “Mechanisms of Severe Acute Respiratory Syndrome Pathogenesis and Innate Immunomodulation”, (2008 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2593566/) Matthew Frieman and Ralph Baric describe how incoming coronaviruses trigger the production of interferons within the cell and initiate other yet unknown responses. These seem to slow down virus action. In turn, viruses continually evolve to overcome the cell’s defences.

If a cell is overcome and dies, this triggers other chemical signals which alert a variety of white blood cells. Some, called macrophages, come to absorb the invading foreign viruses and take the information back to T-cells. The T-cells in turn use this information to help create killer T-cells and antibodies. There are also memory cells that will remember the antibodies required to fight any future infections by the same strain of virus.

Some of my neutrophils from a cold,
photographed at over 1000x magnification
using anoptral contrast

In the meantime, a whole army of another sort of white cell, neutrophils, invade the infected area and gobble up all the debris of damaged cells and the viruses they come across. When you have pus from a spot or your runny nose produces the thick white stuff, that is mostly made up of these short lived neutrophils that have gorged themselves on what is infecting you.

In chemotherapy and radiotherapy, these immune systems are weakened, hence you become more susceptible to infections taking over. So take extra care.

What nations and the international community can do

Whilst the media is enjoying a feeding frenzy in response to the current epidemic, countries and the World Health Organisation have plans and structures in place to trigger action when diseases are spreading. Vaccination programs are not there to poison people, they are there to build up a preventative immunity in individuals against diseases. Every year, new strains of influenza arise naturally by mutation as the virus adapts to us changing humans. Rather than letting a large proportion of the world’s population become ill and therefore retrospectively develop resistance to the newest strain, letting many people die, we humans are proactive. Up and coming new strains of viruses are identified and vaccines produced so that by the time the disease arrives in your part of the world, you are protected in advance and do not get ill.

With totally new viruses, like the COVID-19 coronavirus, there is no immediate vaccine defence. It is therefore vital that a country keeps tabs on new illnesses that arise. They need to have plans in place to deal with the isolation of infected people. They also need to provide care whilst patients go through the illness, to mitigate symptoms until they get well.

Until we have a vaccine, severe cases may be helped by giving them antibodies from people who have recovered from the disease. This method was used against diphtheria in the early 1900's in Alaska. I currently do not know if this being pursued.

In this interconnected world, nations also have a responsibility to alert the WHO early about upcoming diseases. This time round, full marks for the Chinese response, because we were made aware of the issue earlier than in the past. The world could start monitoring for carriers of the illness and put in place travel restrictions. Whilst China has to bear the brunt of the current epidemic with tens of thousands likely to suffer, we are hopefully able to catch the disease before it spreads through our populations.

The UK and WHO have the following information on responses to epidemics and the teams and mechanisms in place. They can be found in public documents such as:



So, should I be concerned?

You should be aware that the COVID-19 virus is currently an epidemic. In the UK, as of today, 15th February 2020, we have two sets of UK citizens  released from 14 day quarantine  and 9 cases of illness recognised and contained in Newcastle.

Look out for public advice from the authorities dealing with the outbreak. The following advice is practical not just in this instance but to minimise your risk of getting ill from any disease that is circulating:
  • Keep healthy by eating and sleeping well and exercising
  • Avoiding locations and people with the illness
  • Regular hand-washing
  • Use of hand sanitisers where there might be a risk in public
If you have returned from a region seriously affected by COVID-19, or met an individual who has subsequently succumbed to the illness, and begin to experience chest and cough symptoms, stay at home and call your surgery. This ensures that you get the right response and treatment and do not accidentally spread the disease further, endangering people in public places, doctors surgeries or hospital reception.



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