Questions about the coronavirus
CORNOVIRUS – ANSWERING QUESTIONS
What is coronavirus?
Coronaviruses a group of viruses that cause
diseases, mainly respiratory, in mammals, humans included, as it has happened
with the SARS-CoV-2. This viral group is responsible of a 30 % of common cold
(most cases nevertheless are produced by rhinoviruses) and most cases are mild.
Since they form a group of viruses, they are not
bacteria, in fact, technically viruses are not alive, therefore antibiotics are
useless.
The illness or disease provoked by SARS-CoV-2 is
called Covid-19.
What kind of viruses are the coronaviruses?
All coronaviruses are RNA viruses, like the influenza
virus. Additionally, they are known as coronavirus due to the spikes present in
their envelope that make it appear like a crown (corona means crown in
Latin).
Due to the lack of some proteins, known as DNA
polymerases, that usually make correction all across the DNA preventing errors,
the rate of mutations in RNA viruses is higher. This is the main reason why it
has been said the SARS-CoV-2 has mutated several times.
How does the SARS-CoV-2 go into our cells?
In order to infect any host (either human or
non-human) viruses need a gateway. These gateways are cell receptor proteins
present in the Surface of the cells that allow the interaction with the
viruses.
In the case of the SARS-CoV-2, the receptor is the
ACE2 which is located on the surfaces of the respiratory cells and interacts
with the spiky proteins of this coronavirus (1). In this way Liang Tao, a
researcher at Westlake University said the following: "If we think of the
human body as a house and 2019-nCoV [another name for SARS-CoV-2] as a robber,
then ACE2 would be the doorknob of the house's door. Once the S-protein grabs
it, the virus can enter the house,".
Other viruses will employ other receptors.
How does the infection develop?
Its main spreading way seems to be in droplets when
people cough or when you touch someone who is infected and you touch your eyes
or nose, in this way the SARS-CoV-2 will reach our lungs.
In our lungs there are billions of epithelial cells
that contain the previously mentioned ACE2 receptor on its surface. The virus
will get attached to this receptor and will introduce its genetic material (RNA
in this case) that will make the cell copy and create more RNA and proteins for
a later reassembling, therefore creating much more viruses.
This will keep happening until the cell receives a
final order to get broken. This process will happen in many lung cells causing
an excessive immune reaction in our lungs, that can cause some severe complications
afterwards. Yet, most people will recover from it with just mild symptoms.
What kind of infections can happen?
Broadly speaking there are two possible infections
that can look like pretty obvious: a mild infection and a severe infection. Mild
infections (including the asymptomatic ones) are roughly the 80% of the cases.
The severe infections complete the other 20 %. These ones include some dramatic
outcomes such as pneumonia and great difficulties to breath (sometimes even
fails) that end up in the need of ventilators. According to the statistics 3 %
of the infected people die.
Corona vs. Flu
Even if most infected people will suffer flu-like
symptoms (fever, cough, generalized pains, sore throat and headache),
SARS-CoV-2 is by far more contagious and its death-rate is also higher that
that of the influenza virus. Among those over 80, the death rate is triggered
up to the 15 %. While this is still quite unknown, children do not get very ill
from this virus, a similar trend to that seen with SARS and MERS, two other
severe diseases caused by coronaviruses. Yet kids can still get infected and
become potential transmitters of the virus and its disease.
The two following articles address the main
differences between Covid-19 and flu, and why kids do not show severe response
against the virus:
-
Covid-19 vs flu: https://www.sciencealert.com/the-new-coronavirus-isn-t-like-the-flu-but-they-have-one-big-thing-in-common
In the following image created by BUSINESS INSIDER,
and used as sources CDC, WHO, American College of Allergy, Asthma and
Immunology (ACAAI), it is possible to see the symptoms of Covid-19 compared to
other conditions:
What do we prefer a fast pandemic or a slow one?
Let’s be cynical: which is the fastest way so that the
virus gets disappeared? Letting it go throughout the population, infecting
practically everyone. However, this would cause an immense death toll, that us,
as a society cannot allow whatsoever. Therefore, a slow pandemic is what we
must try to get. In order to achieve this, protective measures are needed from
the very beginning, including self-quarantine.
Furthermore, the healthcare system capacity in the
case of lacking protective measures, will happen to suffer a higher collapse
when the healthcare professionals, i.e. doctors, nurses, assistants, … get
sick.
REFERENCES
(1) Wrapp, D., Wang, N., Corbett, K. S., Goldsmith, J. A., Hsieh, C.-L.,
Abiona, O., … McLellan, J. S. (2020). Cryo-EM structure of the 2019-nCoV spike
in the prefusion conformation. Science, 367(6483), 1260–1263.
https://doi.org/10.1126/science.abb2507
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