Epidemiology Explained

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Nobody knew there would be a pandemic or epidemic of this proportion.

Donald Trump, American President

If you think of anything that can come along and kill millions of people a pandemic is our greatest risk.

Bill Gates, Chairman of the Gates Foundation

We estimate there are 1.5 million viruses in wildlife that we don’t yet know about. They could cross over into the human population at any moment.

Dr. Peter Dasz, Ecohealth Alliance

World leaders were the first to denounce COVID-19 as a ploy for other countries to shut down theirs. Something that wasn’t a cause for concern because it was so far away. But for the many who worked in infectious diseases this was a worry, they knew it was a precursor for a potential pandemic. In fact, epidemiologist had been warning governments for years. It was never an ‘if’ for these scientists, but when.

COVID-19 is thought to be a zoonotic virus. This is when a virus jumps from an animal to a human and for decades these kinds of viruses have been causing more and more outbreaks.

This time this virus is lethal because it is both easily transmittable and deadly. This is perpetuated by the fact that we have no drugs and no vaccines to fight it. This had already occurred with the 2002 outbreaks of SARS and the 2012 outbreak of MERS. Both were also coronaviruses.

When these viruses were spreading there was indeed mass panic. The deadliness of these viruses caused the rate of transmission to drop, because they killed the hosts. After cases dropped, the interest in the subject did to. However, epidemiologist’s were still concerned and predicted a more destructive coronavirus could develop. And it has. To fully understand this situation (as much as we currently can) we need to grasp the basics of what epidemiologist have tried to tell us for so long. With this post my aim is to shed a little bit more light on the basics of epidemiology.

What is a virus?

It’s one of the earliest living beings on earth and a virus has one goal – to survive and replicate itself. It does this by feeding of it’s host. Us.

The official name of this coronavirus is SARS-COV-2, the disease it causes is COVID-19. The coronavirus is named for it’s crown like spikes, corona is crown in Spanish. It spreads through droplets when we sneeze, cough or speak. It can enter us directly through our eyes, nose or mouth. It also lives on surfaces for hours and so people can infect themselves through touching an affected material and then touching their face.

How does COVID-19 make us ill?

Once inside out body the viruses uses it’s spikes to lock onto human cells. Once it’s in the cells the virus gives itself instructions to produce more copies of itself, potentially invading more and more cells. This invasion leads to symptoms such as; fever, cough and fatigue. When we feel ill, it’s essentially our body warning us of the invasion.

However, you can be infected and spread it without any symptoms. This is called being asymptomatic. You can also confuse these symptoms for the flu, this is why this particular coronavirus has been so successful in transmission so far and has risen in an exponential way.

Some of the people infected then go on to develop a lung infection and those with already compromised immune systems are at a higher risk of a worse infection.

From the research conducted in Hubei, China the risk factors are clear. The older you are the more likely you are to die from the virus. For unknown reasons the risk factor is also higher in men then women.

Why is COVID-19 different to other coronaviruses?

It has the lethal combination of transmission and fatality. However, this doesn’t necessarily make it a successful virus. There are four other coronaviruses that cause human flu’s and common colds, these are classed as being far more successful because they are able to live in their host cells without causing them to die.

Thus, COVID-19 has the potential to be eradicated when we find a vaccine.

Did COVID-19 come from a bat?

This is very likely the case. Bats are teaming with viruses for the simple reason that the virus doesn’t kill them. Scientists in Southern China have been testing bats to see what viruses they carry and which one’s could jump into the human population. They found 100’s of coronaviruses. One named ‘bat coronavirus RaTG13′ had a 96 percent DNA match to COVID-19. The 4 percent difference could be due to a change to the DNA sequence during transmission, as it is believed the bat infected another animal who then infected humans.

The worrying truth is, it’s impossible to predict all the ways a virus might evolve.

Why is this a pandemic?

For a disease to become a pandemic, spreading around the world in months leading to potentially millions of death’s, it has to find an extraordinary balance of contagiousness and deadliness. COVID-19 has done exactly that.

Currently, experts believe COVID-19 is somewhere between the human flu and the 1918 flu in severity. It’s deadlier than the measles but less contagious. However, this estimation can change as we are still in the throws of it.

Some more deadly viruses do not become pandemics because they don’t get far enough. They kill the host before the host can pass the virus on.

How do we end a pandemic?

Through science and technology to put it simply. The deadliness of the typhoid and the bubonic plague were dramatically reduced by the discovery of antibiotics, to the point that no one is concerned about getting it now.

Unfortunately, antibiotics don’t work against this coronavirus. Safe antiviral drugs are very difficult to develop. So, the best way to defeat a virus then becomes, immunity.

When a virus spreads through a population, some people die and some survive. Those who survived have an immune system that has recognized the virus and fought it off. When that happens in enough people, it’s much harder for the virus to spread. This is called herd immunity. The issue with this is, if we were to do this naturally, millions would die. We are also unclear whether we can achieve lifelong immunity with COVID-19, because we don’t with other coronaviruses.

So, it’s crucial we develop a vaccine. If enough people get vaccinated it’s a much safer and quicker way to prevent the spread. It’s a shortcut to herd immunity. However, vaccine’s take a long time to make. Unfortunately, waiting means the virus will keep spreading and killing. The best we can do is slow it down.

This is called social distancing/quarantine. Avoiding close contact with other people so the virus has less chance to spread. This generally means the death rate will remain at a steady level for a longer period of time but overall fewer people will die.

As you’re aware this is what the world is doing right now, trying to flatten the curve and keep it that way. Finding a way to cope while we wait this out.

The question then becomes, at what point on the other side of the curve do we go back to work? That’s where we are now. The way we handle this pandemic will be referred to when a virus even more powerful than this make’s its way into the human population. The key is to not lose hope.

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