Virology: Basics COVID-19
It is week 3 of self- isolation. As usual, I wake up bright and early at 1pm – sometimes 7pm. I drag myself to the kitchen for my daily prophylactic dose of caffeine, my poison of choice, freshly brewed espresso crema (I'm a pretentious coffee drinker and midday isn’t early, I know).
I look at my phone, my whatsapp messages are filled with spam from my Titas forwarding Whatsapp-chainmail of fake coronavirus news, my instagram feed is congested with videos of hate crimes against Asian people ( American definition i.e. not south asians), fake doctors sharing conspiracy theories of 5G causing corona virus and genetic engineering of SARS-CoV-2.
The false information.
I AM TIRED OF IT ALL.
So here I am writing an informative piece, (with @insidemedicine, shoutouts to my favourite editor), in the hopes of putting some good information out there to drive a schism between facts and ABSOLUTE NONSENSE.
And if you share this with your relatives on whatsapp, maybe we can spread some facts via whatsapp chainmail too?
Right off the bat (pun intended), the origin stories of pandemic viruses are much more complicated than people seem to think. Chinese people eating bat soup? Is it 5G? We’re going to discuss it all.
I’ve served my writing in sweet and sour digestible chunks:
- The origin of viruses.
- Viral hosts and mutation
- Coronaviruses and viral transmission
- Symptoms and how do people die from COVID-19
There are many different types of viruses causing loads of common illnesses that we see in our everyday lives, for example, chickenpox, herpes, cold sores, the flu and yes COVID-19.
But where did they come from?
The origin of viruses
All great supervillains have a heart-wrenching origin story, where you begin to doubt whether they are actually good or bad. Unfortunately the origin story of the virus isn’t an academy award winner like the Joker.
Viruses are billions of years old, But tracing their origin can be very difficult as they dont leave behind fossils and their DNA is often mixed with the DNA of organisms they infect ( i.e. the host), which means that studying their ancestry becomes even more difficult.
There are 3 main theories as to where viruses come from
- Progressive hypothesis: Viruses originated from bits of DNA that gained the ability to exit one cell and enter another. Like Skynet from the terminator, a computer program that suddenly gained the ability to infect other electronic devices and eventually take over the world.
- Regressive hypothesis:Viruses came from more complex organisms, such as bacteria, and gradually lost certain features e.g. becoming unable to replicate on their own. Much like, (another movie reference, but this is the last one I promise) in WALL-E where mankind, due to their dependence on hover chairs, have regressed into fat floppy slugs with little to no bone structure.
- Virus first hypothesis: The chicken or the egg, maybe viruses came first? The other two theories stipulate that viruses came after the first complex organism ( bacteria, amoebas etc.), but what if they were there from the beginning of time?
So, the answer to where viruses came from is not a simple one and sheds light on how little we know about viral evolution and how more research is required.
Viral hosts and mutation
The special thing about viruses is that they can’t survive without a “host”, which could be an animal or human. They are like parasites that depend on a host to make more viral copies, and spread into other potential hosts.
Most viruses usually reside in “natural hosts”; these tend to animals which can be both wild and domesticated, like bats, aquatic birds, pigs, sheep, goats etc.
The animals do not actually become sick and act as “reservoirs” for the virus, where it can multiply and divide.
Very rarely, viruses can ‘jump’ across species (zoonotic transmission) and BOOM, we have the potential start of a pandemic. Very rarely do viruses go from infecting animals to humans, there is usually some intermediate host. For example, in the MERS pandemic it is thought the chain of infection looked something like this:
Egyptian tomb bat → Camels → Humans
To give you an idea of how rare zoonotic infections are there are over 1.6million animal viruses in nature, where only 219 of these have been reported to infect humans, that’s about 0.014%. But there are a few viruses that seem to do this often, most notably the influenza virus (the regular flu) and corona virus families. For example, there have been three different pandemics caused by coronaviruses.
So why do we keep getting the flu? Why isn't it like chicken pox, that most people usually only get once?
Here’s an analogy, your phone rings.
07999999999, it’s your toxic ex-you block their number.
Viruses mutate and change as fast as your toxic ex can buy a new sim card to call you with. And, now a new number is calling you
You don’t recognise this number, and you pick up the phone…and now you’re infected with their toxic promises and hopes of rekindling a relationship. Ladies and gents, please remove all toxic people from your life they are worse than SARS
A family of viruses - named ‘corona’ because they are covered in spikes which look like crowns or halos. Corona in latin means crown.
Within this family we find the virus severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2) which is responsible for causing the illness COVID-19 – our current pandemic.
Pandemic= Affects many people across continents or the whole world.
Epidemic= Affects many people at the same time usually within a certain region or community
Severe acute respiratory syndrome-coronavirus 1(SARS-CoV1), is also within the coronavirus family and caused an earlier less extensive outbreak of around 8,000 cases compared to the 1,210,956 cases we currently see with COVID-19 (figures from 06/04/20 WHO).
Going back to our toxic ex calling analogy, SARS-CoV-1 is now SARS-CoV-2 and has come to mess with your life again, in an even more toxic way. It has come to mess with your lungs.
It is important to note the different ways viruses can spread:
- Airborne: via droplets from sneezing or coughing, like the flu and tuberculosis
- Fecal: oral routes- usually when there is poor sanitation for example if someone goes to the toilet and doesn't wash their hands and proceeds to touch their mouth. Polio and Hep A are transmitted this way
- Sexually: transmitted, including oral and anal transmission, such as human papollioma virus, Hepatitis B and HIV.
- Vertical transmission: from mother to baby during child birth when their blood mixes or during breastfeeding. HIV and hepatitis B are also transmitted this way.
Like the flu, COVID-19 is transmitted through droplets in the air, made when people cough, talk or sneeze.It can also spread from touching contaminated surfaces and then touching your nose, eyes or mouth. This is why wearing a face mask is a great precaution to protect others from your own droplets if you are infected.
Symptoms and how do people die from COVID-19 ?
A study of 99 cases in China reported the following symptoms :
- Flu- like symptoms
- Dry cough
- Shortness of breath
- Loss of smell/ taste
- Nasal congestion
- Diarrhoea ( so I guess you may need some extra toilet paper if you don't have a bidet or tabo)
- Asymptomatic - no symptoms at all
The danger of COVID-19 and its propensity to kill is due the severe immune reactions to the virus in some patients. This leads to a more severe clinical picture such as:
- Pneumonia: the lungs are inflamed and filled with pus instead of air due to the viral infection.
- Acute respiratory distress syndrome: the lungs rapidly become so inflamed that they stop working properly.
- Septic shock: the body is overwhelmed by the infection leading to dangerously low blood pressure. Not enough blood pumping around the body is fatal.
Needless to say, if the lungs don’t work then the patient can’t breathe, and this could lead to death within minutes. Luckily hospitals use ventilators for these situations which help the patients to breathe and are lifesaving.
But what happens when there are not enough ventilators to go around?
In a report of 72,314 cases from the Chinese Center for Disease Control and Prevention, the following figures were found reflecting the experienced symptoms of COVID-19:
- Mild (no or mild pneumonia): 81%
- Severe disease (g. with dyspnoea, hypoxia or >50% lung involvement on imaging within 24 to 48 hours): 14%
- Critical disease (e.g.with respiratory failure, shock or multi-organ dysfunction): 5%
From this report if we assume around 19% of those infected will have severe enough symptoms where they might require ventilation, and in the UK there are 98,476 confirmed cases in the UK (statistics from 16/04/20). This may mean up to 18,710 people will require ventilation.
There are currently only 10,000 ventilators available in the NHS and we are unsure when we will reach the peak of this crisis - it is clear that the number of ventilators is not enough. When hospitals become more and more filled with infected patients who need ventilators we may not have enough, which may mean unfortunately more people die.
The death rate of COVID-19 is currently estimated to be around 3.4%, and although this sounds like a small percentage, of the infected 98,476, that is still over 3,348 lives lost to disease that is so preventable.
Some final thoughts
The most frustrating thing about today’s pandemic, for me atleast, is not staying at home being surrounded by the same four walls. It is all the preventable deaths, all the lives that can be saved if people took social distancing seriously, if the government gave the NHS more funding and acted sooner. It is the overwhelming feeling of being able to do something, but alone, nothing at all.
A moral flaw in the majority rule is the tyranny of the majority, where a majority of people do what they want at the expense of a minority. If the minority of people are thousands of human lives, is this morally right?
Would you go sunbathe in the park at the expense of the lives of the people you come into contact with?
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- Wessner, D. R. (2010) The Origins of Viruses. Nature Education 3(9):37
- ·Who.int. 2020. WHO | SARS (Severe Acute Respiratory Syndrome). [online] Ava ilable at: <https://www.who.int/ith/diseases/sars/en/>
- Who.int. 2020. Novel Coronavirus (2019-Ncov) Situation Reports. [online] Available at: <https://www.who.int/emergencies/diseases/novel-coronavirus-2019/situation-reports>
- Sanjuán R, Domingo-Calap P. Mechanisms of viral mutation. Cell Mol Life Sci. 2016;73(23):4433–4448. doi:10.1007/s00018-016-2299-6
- Warren CJ, Sawyer SL (2019) How host genetics dictates successful viral zoonosis. PLoS Biol 17(4): e3000217. https://doi.org/10.1371/journal.pbio.3000217
- Chen N, Zhou M, Dong X, Qu J, Gong F, Han Y et al. Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study. The Lancet. 2020;395(10223):507-513.