The current outbreak of COVID-19 has sparked
global anxiety and concern. What are the realities of the pandemic? We
investigate.
This article was updated on June 17, 2020
In December 2019, reports emerged
that a coronavirus that specialists had never before seen in humans had begun
to spread among the population of Wuhan, a large city in the Chinese province
of Hubei.
Since then, the virus has spread to other countries, inside and
outside of Asia, leading the World Health Organization (WHO) to
declare this as a pandemic.
To date, the novel coronavirus — called severe acute respiratory
syndrome coronavirus 2 (SARS-CoV-2) — has been responsible for millions of infections globally, causing
hundreds of thousands of deaths. The highest number of deaths has occurred in
the United States.
What do we really know about this virus? To what extent is it
likely to affect the global population?
Medical News Today have contacted the WHO, collected information from public
health organizations, and looked into the newest studies in peer reviewed
journals to answer these and other questions from our readers.
Stay informed with live updates on the current COVID-19
outbreak and visit our coronavirus
hub for more advice on prevention and treatment.
1.
What is the new virus?
SARS-CoV-2 is a coronavirus that causes coronavirus disease 2019
(COVID-19). Coronaviruses are a family of viruses that target and affect
mammals’ respiratory systems. According to their specific characteristics,
there are four main ranks, or genera, of coronavirus: alpha, beta, delta, and
gamma.
Most of these only affect animals, but a few can also pass to
humans. Those that are transmissible to humans belong to only two of these genera: alpha and beta.
Only two coronaviruses have previously caused global outbreaks.
The first of these was the SARS coronavirus — responsible for severe
acute respiratory syndrome (SARS) — which started spreading in 2002, also in
China.
The SARS virus epidemic primarily affected the populations of
mainland China and Hong Kong, and it died off in 2003.
The other was the MERS coronavirus —
responsible for Middle East respiratory syndrome (MERS) — which emerged in
Saudi Arabia in 2012. The virus has affected at least 2,494 people since then.
2. Where did the virus originate?
When humans contract a coronavirus, it typically happens due to
contact with an infected animal.
Some of the most common carriers are bats, though they do not
typically transmit coronaviruses directly to humans. Instead, the transmission
might occur via an intermediary animal, which will usually, though not always,
be a domestic one.
The SARS coronavirus spread to humans via civet cats, while the
MERS virus spread via dromedaries. However, it can be difficult to determine
the animal from which a coronavirus starts spreading among humans.
In the case of the new coronavirus, initial reports from China
tied the outbreak to a seafood market in central Wuhan. As a result, local
authorities closed down the market on January 1, 2020.
However, later assessments have suggested that this market
was unlikely to be the single source of the coronavirus outbreak, as some
people with the virus early on had no connection with it.
Specialists have not yet been able to determine the true source
of the virus or even confirm whether there was a single original reservoir.
When MNT contacted the WHO for comment, their
spokespeople emphasized:
“We don’t yet know [what the specific source
of SARS-CoV-2 was]. Researchers in China are studying this but have not yet
identified a source.”
3. How does the virus transmit?
Although it likely originated in animals, SARS-CoV-2 mainly
seems to travel from person to person. However, some questions about its
transmission remain unanswered.
According to WHO spokespeople, “Researchers are still studying
the exact parameters of human-to-human transmission.”
“In Wuhan at the beginning of the outbreak, some people became
ill from exposure to a source, most likely an animal, carrying the disease.
This has been followed by transmission between people,” they explained.
“As with other coronaviruses, the transmission
is through the respiratory route, meaning the virus is concentrated in the
airways (nose and lungs) and can pass to another person via droplets from their
nose or mouth, for example. We still need more analysis of the epidemiological
data to understand the full extent of this transmission and how people are
infected.”
The WHO state that “The
risk of catching COVID-19 from someone with no symptoms at all is very low.
However, many people with COVID-19 experience only mild symptoms. […] It is,
therefore, possible to catch COVID-19 from someone who has, for example, just a
mild cough and does not feel ill.”
According to the Centers for Disease Control and
Prevention (CDC), some recent studies suggest that people may still
spread COVID-19 if they are not showing symptoms.
This means that people should adopt careful hygiene practices
and engage in physical distancing — even around people who do not appear to be
sick.
The CDC also report that SARS-CoV-2 spreads easily among people.
They state that the virus “is spreading more efficiently than influenza, but
not as efficiently as measles, which is highly contagious.”
People may begin to experience symptoms 2–14 days after
exposure to the virus.
The CDC recommend that
all people wear cloth face masks in public places where it is difficult to
maintain a 6-foot (2-meter) distance from others. This will help slow the
spread of the virus from asymptomatic people and people who do not know that
they have contracted it. People should wear cloth face masks while continuing
to practice physical distancing. Instructions for making masks at home are
available here. Note: It is
critical that surgical masks and N95 respirators are reserved for healthcare
workers.
4. How does it compare with other viruses?
Researchers from Chinese institutions have used state-of-the-art
genome sequencing tools to identify the DNA structure of the novel coronavirus.
It has emerged that SARS-CoV-2 is most similar to two bat
coronaviruses: bat-SL-CoVZC45 and bat-SL-CoVZXC21. Its genomic sequence
is 88% the same as
theirs.
The same study shows that the new virus’s DNA is about 79% the
same as that of the SARS coronavirus and approximately 50% the same as that of
the MERS virus.
Recently, a study by researchers in China suggested that pangolins may have been the initial
propagators of SARS-CoV-2 among humans, as its genomic sequence appears to be
99% like that of a coronavirus specific to these animals.
Since then, however, other specialists have cast doubts about
this idea, citing inconclusive evidence.
5.
What are its symptoms?
Like other coronaviruses, the novel coronavirus causes
respiratory disease, and the symptoms affect a person’s respiratory health.
According to the CDC, the symptoms of
COVID-19 can include:
- a cough
- shortness of breath or difficulty breathing
- fatigue
- a headache
- congestion or a runny nose
- a fever
- chills
- muscle pain
- a sore throat
- a new loss of taste or smell
- nausea or vomiting
- diarrhea
Less commonly, symptoms may include gastrointestinal symptoms,
such as nausea, vomiting, or diarrhea.
A study published in The Lancet reports
that around 81% of people with COVID-19 have mild symptoms and do not require
hospitalization.
“Current information suggests that the virus can cause mild
flu-like symptoms, as well as more severe disease. Most [people] seem to have
mild disease, and about 20% appear to progress to more severe disease,
including pneumonia, respiratory failure, and, in some cases, death,” WHO spokespeople
told MNT.
In an official WHO Q&A
session, Dr. Maria Van Kerkhove explained that because the symptoms of COVID-19
can be very generic, it can be difficult to distinguish between them and the
symptoms of other respiratory infections.
To understand exactly what a person is dealing with, she said,
specialists test viral samples, checking to see whether the virus’s DNA
structure matches that of SARS-CoV-2.
“When someone comes in with a respiratory disease, it’s very
difficult, if not impossible, initially, to determine what they’re infected
with. So, because of this, what we rely on are diagnostics [molecular tests],”
said Dr. Van Kerkhove.
Source: Medical News Today
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