Find out what Covid-19 really is and how you can protect yourself
One thing COVID-19 isn’t is a virus. There – I said it! Not that you would know from everything that’s buzzing around the media right now.
So if it’s not a virus, what is it?
COVID-19 is the disease you develop from being infected with the SARS-CoV-2 virus. Imagine it like HIV which is the virus that causes the disease AIDS.
Or the Streptococcus bacterium that causes tonsillitis.
So what does SARS-CoV stand for and how did it start?
SARS-CoV stands for Severe Acute Respiratory Syndrome caused by the Coronavirus and SARS-CoV-2 is the latest strain of the virus.
Scientists have been looking at the genome sequencing of this virus and have traced its origins back many tens of thousands of years. Coronavirus is part of a family of viruses that cause various diseases in various animals and, more recently, humans.
Scroll forward thousands of years. The first human Coronavirus was discovered by Tyrrell and Bynoe, back in the 1960s. They took respiratory tract swabs from human volunteers who were suffering from the common cold. They discovered a common infectious agent and the story of human Coronavirus began.
Whilst this was a fantastic discovery, it only answered a few questions about an otherwise innocent disease. Oh, and also to gain its name due to the crown-like projections emanating from the virus cell’s membrane. Coronavirus!
Forward again to the 21st Century. The first strain of SARS-CoV appeared in 2002 in a small city in the Guangdong Province of China (population of around 7.2 million) on the border with Hong Kong where a farmer became ill with a severe respiratory infection. The virus spread around the world infecting 8,000 people (as far as we know) and was attributed to 774 deaths in 17 countries.
SARS-CoV came and went without a huge global concern given the overall numbers affected.
Fast forward to 2012: Saudi Arabia. The first case of MERS (Middle Eastern Respiratory Syndrome) was reported. This spread around many countries and even reached the UK in 2015. Its official name is MERS-CoV. Since its discovery, it has infected around 2,494 people (laboratory-confirmed cases) and 858 reported deaths over 27 countries. Again, no global crisis because of such low numbers.
Now jump forward to late 2019 and back to China. This time an outbreak in the sprawling capital of Central China’s Hubei Province, Wuhan (probably from a meat market). The first example of the current mutation of the virus, SARS-CoV-2. Let’s dive in and look at why this strain of Coronavirus is causing worldwide chaos when SARS and MERS did not.
Lots of people say that flu is a huge global killer, so what’s the big deal about Coronavirus?
The World Health Organisation estimates the global deaths from seasonal flu at a minimum of 290,000 annually,
This is clearly a big number. So why the panic around Coronavirus? As we will see, for various reasons, left unchecked, the science around this new disease is that it would kill far more people than the flu. Why is this?
First up, It’s not about how many people die from it. It’s about how many catch it and survive!
In the case of SARS, there were 774 deaths out of 8,000 infected. This is a mortality rate of 9.7%.
Turning to MERS, there were 858 deaths out of 2,494 deaths, a staggering mortality rate of 35%! That means that if 100 people catch it, 35 will die.
Initially, the data suggests that this new strain of Coronavirus, SARS-COV-2, has a mortality rate of between 2-4%. On the face of it, the new virus doesn’t sound like a big deal.
However, this ignores the likely number of people infected worldwide. 2% of 1,000 would be a minor public health issue. However SARS-COV-2 is incredibly infectious and without massive interventions, many millions will be infected and 2% of millions is a huge loss of human life.
The Infection Rate
In order to understand why SARS-CoV-2 is so infectious, we need to understand something called the infection rate, calculate it for this virus and then work out how many people could potentially contract the illness and thus work out how many could possibly die.
The infection rate is how many people can a single person infect if they have the illness. We call this the R0 (R nought) number or reproduction number.
For example, flu has an R0 1.3.
So for each person that has the flu, they will pass that on to another 1.3 persons. Then they, in turn, will pass that on to another 1.3 people. And on it goes.
To add some context, measles has an R0 between 12-18 depending on various factors. So measles is incredibly infectious which is why public health authorities are so concerned to ensure close to 100% of the population are vaccinated. Without mass vaccination, millions would die from measles each year.
So with this data can we predict how many will catch this new virus and how many may die?
Well, no, not quite. There is something else we have to factor in and that’s the incubation time.
Incubation time determines how many people will get sick over what timeframe. The flu has an incubation period of just a few days. And you may not show any symptoms over those few days but are still passing the virus on.
In just a few days the flu can infect many people. However, you know you have it sooner and can isolate so as not to infect others. In fact, most of us are too ill to want to go out once we have the symptoms. So we often stop spreading it as widely, at that stage, because we naturally travel less through the community.
So, in the case of viruses with long incubation periods, the longer the period we can infect other people. In the case of viruses where some or a large proportion of those infected have no symptoms during the incubation period, the more people we unknowingly infect.
Putting it all Together
We can now understand why SARS-CoV-2 is posing a worldwide pandemic and an unprecedented public health emergency not seen since the 1918-19 Spanish flu epidemic which killed an estimated 20-50 million people globally.
This new variant of SARS-CoV has an R0 of 2-2.5, has an incubation period between 1-14 days and, particularly in young people can be completely symptomless.
So can we now see how a) it will infect more people, b) they won’t know they are infected until they have had the virus for a while.
The combination of these factors means that if societies do not take extreme measures to socially isolate citizens, the virus will spread extremely rapidly and widely. Public Health England and other reputable medical sources estimate infection rates where such measures are not taken of approximately 80%
Even if the estimated death rate for SARS-CoV-2 of 2-4% is exaggerated – let’s apply an overall death rate of 1% – this would mean around 54 million of the UK population would be infected and around 540,000 would die. Taking the lower of the 2-4% range, over a million people would perish in the UK.
The idea that SARS-CoV-2 is just like the flu is dangerously wrong. This virus is a very dangerous beast and requires the huge and urgent international response it has generated.
How does the SARS-CoV virus work?
This virus can’t walk and it most certainly can’t fly. What’s more, it can only use those little crown projections coming out of it to bond to very specific cells. It can’t just bond to any old cell in your body.
It’s a respiratory tract infection. It can only bind to those special cells.
How does the SARS-CoV virus get into our body?
Usually, you put it there! Viruses are very intelligently adaptable. They have been on this planet longer than we have. They need to reproduce and then get out to find new hosts. Not just new host cells within the first animal they find: if they infect too many cells that the animal will die taking the virus along with it. Somehow they have to find a way to get out of this host animal and into another one. It’s incredibly difficult to infect another species, so it needs to find lots of the same species of animal in one place.
With this in mind, viruses tend to infect areas where they can easily get in but also get out. It’s no coincidence that Norovirus makes you expel all your bodily contents from both orifices of your digestive system! Its evolutionary capability is to reach as far and wide as possible.
The same mechanism drives coughing and sneezing when we have the flu. This enables the virus to reach other potential hosts.
On the other hand, when the virus leaves the body, it is under threat. It can’t live for very long outside the body. So it needs to find a new host before it dies. If the environmental factors are right, some viruses can live outside a host for many days. SARS-CoV 2 mostly relies on you coughing out large droplets of water to carry it and give it some temporary accommodation. Depending on what it lands on, its survival is a matter of hours or several days.
Direct contact can allow the virus to be passed from one person to another. The closer the contact, the more likely. Kissing is a virus’ best and easiest route. But the most likely route is usually your hands. That’s where the tyres meet the tarmac, so to speak. It’s how we interact with our surroundings.
An infected person touches another person or a hard surface and the virus waits for you to touch your face to facilitate migration into its new host animal – YOU!
What happens once we become infected by SARS-CoV?
Once inside your body, the virus binds to cells that have similar receptors to itself.
This is what’s called an enveloped virus – it has a special fat layer around the outside. This helps protect it between host cells but it also looks like a protein that should not be attacked by the immune system. Initially anyway. The virus is not of human origin so our immune system doesn’t recognise it. The infected cell is then fooled into accepting the virus.
This is where the virus gets to work. It has found a new host and the new cells are healthy. So the virus starts to hijack the cell. The virus then uses the cell’s factory to start printing out millions of copies of itself. But it has to hide these new copies so they don’t get attacked. This is another vulnerable stage for the virus. It uses our cells to coat the new copies, to hide them and releases them in search of new hosts. The virus ruthlessly keeps printing copies until it kills the host cell that it’s hijacked. It hopes that the new copies have infected new cells and thus the cycle continues.
As more and more cells are destroyed in the production of new viruses, the system begins to break down. So, in the case of a respiratory tract infection, lung cells. Obviously, fewer functioning lung cells means reduced functionality of the lungs.
In the case of SARS-CoV 2, the evidence suggests that this is the most likely cause of death. Those with existing reduced lung function, like the elderly or those with lung diseases, are at the most risk. But any underlying health condition that reduces your body’s ability to fight infections, increases the risk.
But it’s not all bad. The clock is ticking for the virus. As it kills more cells, our immune system will be enlightened to that and start to react. Actively looking for and killing new viruses that are released from damaged host cells. Now it’s the battle of the fittest. This is why those who are young, fit or healthy have strong immune systems and their systems are best able to fight the virus and kill it off. Those people either have no symptoms or mild or moderate symptoms. They will not need medical treatment although drinking lots of fluid and taking paracetamol can be used to reduce headaches and aching limbs. Those who are less fit, older, with less strong immune systems will experience much more serious symptoms and may need to be hospitalised.
Symptoms of SARS-CoV-2
The reports of symptoms are far and wide. Ranging from no symptoms at all, all the way up to death.
However, the 2 most common symptoms are:
• a high temperature – this means you feel hot to touch on your chest or back (you do not need to measure your temperature)
• a new, continuous cough – this means coughing a lot for more than an hour, or 3 or more coughing episodes in 24 hours (if you usually have a cough, it may be worse than usual)
The only way to know if you really have SARS-CoV 2 is by testing.
The UK is currently only testing hospital admissions that are displaying the common symptoms. There is no test available at the moment for people who have already contracted the illness but recovered. And until we have one it’s very difficult to accurately calculate the mortality rate, infection rate and incubation period. It may be that many more have had this virus than first thought, which would significantly reduce the mortality rate. The UK Government has announced that it is very close to the release of mass self-testing to see whether individuals have had the illness because the test will detect whether they have developed antibodies (prior to last December, no human had had the virus so no-one was immune).
I think I have Covid-19 – what should I do?
If you have symptoms of coronavirus (a high temperature or a new, continuous cough), use the 111 coronavirus service: NHS 111 Service
DO NOT go to places like a GP surgery, pharmacy or hospital.
What can I do to prevent getting Covid-19?
At the moment, there is no vaccine or anti-viral drug for the SARS-CoV-2 virus.
Once you are infected and develop Covid-19 all you can do is alleviate symptoms. So if you have a fever, for example, try to reduce it.
Government advice is changing daily with daily bulletins, updates and advice.
But as with any virus, we can take certain basic precautions.
Hand Washing is Your Best Weapon
Soap and water will remove the virus. Alcohol hand sanitiser can damage the fatty shell and make the virus more vulnerable. Washing robs much of the natural oils from our skin causing it to dry out. Dry skin is incredibly difficult to clean, so moisturiser is just as important as soap! After washing, try to moisturise to keep your skin hydrated and make it easier to clean.
Should I wear a face mask?
Surgical face masks won’t stop you contracting the virus. The mask is to stop the healthcare worker coughing onto their vulnerable patients. Evidence has shown that face masks can increase the risk as they get wet (remember this virus needs those water droplets) and human behaviour. Those not accustomed to wearing them touch their face more frequently than they would normally have done. Although if you have the virus you can prevent others from contracting it by using a mask or covering your face when coughing or sneezing.
I’ve already mentioned how water droplets can’t travel far. So social distancing is another great weapon to combat the increased spread of the virus.
The droplets from coughing and sneezing can reach up to 2 meters from the infected host. So maintaining at least that distance in an open space should prevent infection.
Stay at home as much as you can. Only leave for essential items or to help someone who is vulnerable and cannot care for themselves. And remember that you can be infected and spread this virus with little or no symptoms.
Understand the R0 factor and incubation period as I discussed earlier.
If one member of your household contracts it, the chances are the rest will.
Symptoms usually last for 5-7 days. But in those where they have been complications, it can take several weeks to recover.
What About Herd Immunity?
So if most of us will be ok, then why not just go get it?
Herd immunity does work. But it works much more safely if we can vaccinate rather than take the gamble people will survive the illness. It’s estimated about 20% of those that contract this virus will require hospitalisation. With about a quarter of those which will require Intensive Care.
In number terms, it is estimated that instead of 540,000 plus dying if nothing is done, using herd immunity and then protecting the vulnerable would reduce the number of deaths by around half to 250,000.
This is why the UK Government has introduced a significant lockdown of the country. The experts have estimated that if the UK population follows the guidelines strictly, the number of overall deaths could be substantially limited, possibly as low as around 25,000.
So what is the difference between the herd immunity model and the lockdown model?
Whilst our healthcare system is currently coping, we are only in the very early stage of the epidemic in the UK at the moment.
If the growth of those catching the virus is not strongly controlled by changing the population’s exposure to each other over the cycle of the virus until there is a vaccine available (estimated at 1 year to 18 months) or effective anti-viral medication (period unknown), the health service will rapidly become overwhelmed in terms of human resources, beds, oxygen, ventilators and personal protection equipment. Many, many thousands of people will needlessly die both from the virus and also from other illnesses which the health system will not be able to treat.
Herd immunity involves allowing 80% of the population to carry on with business as usual whilst the most vulnerable are in lockdown. However, this will mean that too many people will catch the virus and get ill at the same time. Around 20% of those catching it will become seriously ill and the health service will rapidly become overwhelmed.
Hence the new model: everyone apart from essential workers are placed into periods of home lockdown. This is designed to ensure that the virus spreads in as controlled and limited way as possible so that over the medium term the health services can cope and the maximum number of lives can be saved.
If most people recover after 7 days, then our beds should clear relatively quickly and will be ready for the next wave. It would be easier to deal with many small waves than one big one. Any good sailor will tell you that.
Each country has to deal with this in a different way. Individual demographics (some cultures have more people living in a single homestead), social demographics (elderly populations are more vulnerable), transport systems (better transport the larger the infection rate). I could go on. But the variables will make timing and tactics very different from country to country.
When will this end?
The truth is, we don’t know. What we do know about viruses is that they die off either by lack of hosts (because they are dead or too far away to infect so the virus naturally dies) or by having antibodies against the virus in our immune system via vaccination or surviving the virus.
But even then this could change seasonally and our antibodies may only offer short term protection like the flu.
The better question perhaps is how will this end? Here our answer is driven by what we know about the virus as summarised above. If through lockdown, the spread can be reversed, if the reversal is maintained eventually the population will be virus-free. How does the spread reverse: the answer is the R0 becomes less than 1. We know that uncontrolled the SARS-CoV-2 has an R0 of 2.3 meaning one person will on average infect 2.3 other people. If we successfully self-isolate, the R0 will drop. In a strange hypothetical world where every person the entire world self-isolated for six weeks, the R0 would eventually hit 0 i.e. no-one is infecting anyone else!
In the real world, the likelihood of the virus dying out in the human population is highly remote because different countries are imposing different degrees of lockdown. Thailand is an example of a country which has closed its borders, internal curfews, etc. It has had 1,045 cases and 4 deaths in an overall population of around 69 million. It is of course much closer to the original epicentre of the illness, China, than the UK which has a population of around 67.7 million, 9,529 cases and 465 deaths. The UK’s policy has shifted from a more liberal herd immunity approach initially to a much greater degree of lockdown in the last week.
We must bear in mind that European countries, a group of liberal democracies, will be balancing restrictions against the constraints on these actions in free societies. Even within Europe, the UK is more permissive than, say, Italy and Spain.
Bottom line, given different approaches, the virus will not disappear anytime soon. So the virus will not be totally defeated for many years to come. The threat it poses can be substantially reduced if we all follow the UK Government’s directions and, we hope, many of these restrictions can be reduced and subsequently totally lifted once vaccines and anti-viral medications are in place within the next year to 18 months.
Wishing you all well. Stay home, stay safe.
Infection Control Lead for Safe and Sound