T
|
he current outbreak of infections with a novel type of
coronavirus has sparked global anxiety and concern that the virus might spread
too far and too fast and cause dramatic harm before health officials find a way
to stop it. But what are the realities of the new coronavirus outbreak? We
investigate.
Share on PinterestWhat are the realities of the new
coronavirus outbreak?
Last updated on March 5,
2020
For
live updates on the latest developments regarding the novel coronavirus and
COVID-19, click here.
In
December last year, reports started
to emerge 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, both in and outside Asia,
leading authorities to describe this as an outbreak. At the end of January this
year, the World Health Organization (WHO) declared the situation to be a public health emergency.
To
date, the novel coronavirus — currently dubbed “severe acute respiratory
syndrome coronavirus 2,” or SARS-CoV-2 for short — has been responsible for 78,191
infections in China and 2,918 across 37 other world countries. In China, the
virus has so far caused 2,718 deaths. It also led to one fatality in the
Philippines.
But
what do we really know about this virus? And how is it likely to affect the
global population?
Medical News Today have contacted the
WHO, used the information that public health organizations have offered, and
looked at the newest studies that have featured in peer-reviewed journals to
answer these and other questions from our readers.
SARS-CoV-2
is a coronavirus that causes coronavirus disease 2019 (COVID-19).
Coronaviruses, in general, are a family of viruses that target and affect
mammals’ respiratory systems. According to their specific characteristics,
there are four main “ranks” (genera) of coronaviruses, which are called 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 first started spreading
back 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 one was the MERS coronavirus —
or Middle East respiratory syndrome coronavirus — which emerged in Saudi Arabia
in 2012. This virus has affected at least 2,494 people since then.
When
humans do become infected with a coronavirus, this typically happens via
contact with an infected animal.
Some of
the most common carriers are bats,
although 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 infection first starts spreading.
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.
However, later
assessments have since
suggested that this market was unlikely to be the single source of the
coronavirus outbreak, as some of the people infected with the virus had not been
frequenting the market.
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.”
While
it likely originated in animals, the transmission of the new coronavirus from
person to person can occur, though some questions about its transmission remain
unanswered.
According
to the WHO spokespeople who responded to MNT queries, “[r]esearchers 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, adding:
“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.”
In a
press briefing from February 6, WHO consultant Dr. Maria Van Kerkhove said
that, for now, “[w]e do know that mild individuals shed virus, we know that
severe individuals shed virus. […] We know that the more symptoms you have, the
more likely you are to transmit.”
In
their “Q&A on coronaviruses,”
the WHO state that “[t]he risk of catching COVID-19 from someone with no symptoms
at all is very low.”
In an interview for the JAMA Network — also broadcast on February 6 — Dr. Anthony
Fauci, the director of the National Institute of Allergy and Infectious
Diseases, said that based on data that they have received from Chinese
specialists, the new coronavirus’s “incubation period is probably between 5 and
6 — maybe closer to 5 — days.“
That
is, the virus likely takes about 5–6 days to give rise to symptoms once it has
infected a person.
Although
the WHO note that experts estimate that the new virus’s incubation period may
last anywhere between 1 and 14 days, they suggest in their coronavirus Q&A
section that the most likely duration is about 5 days.
Researchers
from Chinese institutions were able to use 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 known as 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% like 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, as its genomic sequence appeared to be 99% like that
of a coronavirus specific to these animals.
Since
then, however, other specialists have cast doubts over this idea, citing inconclusive evidence.
Like
previous coronaviruses, the novel coronavirus causes respiratory disease, and
the symptoms affect respiratory health.
According
to the Centers for Disease Control and
Prevention (CDC), the main symptoms of COVID-19 are fever, cough,
and shortness of breath.
“Current information suggests that the virus can
cause mild, flu-like symptoms, as well as more severe disease. Most patients
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
their press briefing from February 27, WHO officials also pointed out that a
runny nose is not usually a symptom of COVID-19.
"Are
we ready to treat patients with severe or critical #COVID19?
Do our hospitals & clinics have the right procedures to prevent & control #coronavirus infections?
Do our people have the right information? Do they know what the disease looks like?"-@DrTedros
Do our hospitals & clinics have the right procedures to prevent & control #coronavirus infections?
Do our people have the right information? Do they know what the disease looks like?"-@DrTedros
"It’s
not usually a runny 
. In 90% of #COVID19 cases it’s a 
& in 70% of cases a dry cough.
Are we ready to fight rumours & misinformation with clear & simple messages that people can understand?"-@DrTedros #coronavirus
. In 90% of #COVID19 cases it’s a & in 70% of cases a dry cough.Are we ready to fight rumours & misinformation with clear & simple messages that people can understand?"-@DrTedros #coronavirus
In an
official WHO Q&A session, Dr.
Van Kerkhove explained that as 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 or not.
“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.
Many
people are worried about whether the current outbreak will evolve into a
pandemic, and public worries have become amplified by the CDC’s telebriefing from February 25, which
asked U.S. citizens to be prepared for that possibility.
However,
WHO officials argue that declaring a COVID-19 pandemic may not be a
constructive approach to the current public health emergency.
In a declaration on February 26,
WHO’s director-general, Dr. Tedros Adhanom Ghebreyesus stated that “[u]sing the
word pandemic carelessly has no tangible benefit, but it does have significant
risk in terms of amplifying unnecessary and unjustified fear and stigma, and
paralyzing systems.”
Many
questions also remain about how SARS-CoV-2 compares with other viruses in terms
of its rates of infection and mortality.
In
response to questions about this, the WHO spokespeople told MNT that “[t]his is a new
disease, and our understanding is changing rapidly. We will continue to analyze
information on both current and any new cases.”
“We don’t yet know many
details about the mortality rate from SARS-CoV-2, and studies are ongoing now.
With MERS, we know that approximately 35% of reported patients with [MERS
coronavirus] infection have died. For SARS, WHO estimated that the case
fatality ratio of SARS ranges from 0% to 50% depending on the age group
affected, with an overall estimate of case fatality of 14% to 15%.”
– WHO spokespeople
So far,
the number of infections and deaths that COVID-19 has caused is also smaller
than the number resulting from recent outbreaks of particularly harmful
influenza viruses, such as swine flu (H1N1).
“On
H1N1, From April 12, 2009, to April 10, 2010, the CDC estimated there were 60.8
million cases, 274,304 hospitalizations, and 12,469 deaths in the United States
due to the (H1N1)pdm09 virus. Additionally, the CDC estimated that
151,700–575,400 people worldwide died from (H1N1)pdm09 virus infection during the
first year the virus circulated,” the WHO spokespeople told MNT.
According
to recent assessments,
SARS-CoV-2 seems to be more infectious than other coronaviruses — such as those
that cause SARS and MERS — but less likely to lead to death.
Some
estimates suggest that the death rate of the new coronavirus is in the range
of 2–3%, but there are no
official numbers in this regard, as it is hard to tell how the outbreak will
develop.
In the WHO press briefing from February 6, WHO
officials reiterated that the people most at risk of experiencing severe
illness due to a SARS-CoV-2 infection are older adults and individuals who have
other health conditions that compromise their immune system.
“Being
over 80 is the highest risk factor” for [SARS-CoV-2]-related death, WHO
officials also said in the press briefing.
Other reports note that very few children
have become infected with the new coronavirus. However, a recent preliminary study —
not yet peer-reviewed or published in a journal — claims that children face the
same risk of infection as adults.
Among
adults, some reports suggest
that men might be more at risk than women.
Official
WHO prevention guidelines suggest
that to avoid infection with the coronavirus, individuals should apply the same
best practices for personal hygiene that they would to keep any other virus at
bay.
According
to the WHO spokespeople who replied to MNT queries:
“Standard recommendations
to prevent infection spread include regular hand washing, covering [the] mouth
and nose when coughing and sneezing, [and] thoroughly cooking meat and eggs.
Avoid close contact with anyone showing symptoms of respiratory illness, such
as coughing and sneezing.”
As for
wearing protective masks, WHO guidelines state
that people need only do this if they are caring for someone who has COVID-19.
Masks
should cover the nose and mouth and be tightly secured. People should
thoroughly wash their hands before putting on a new mask, make sure that they
dispose of used masks appropriately, and clean their hands once again after
removing them.
There
are currently no targeted, specialized treatments for infections resulting from
the new coronavirus. When doctors detect a SARS-CoV-2 infection, they aim to
treat the symptoms as they arise.
In the WHO Q&A, Dr. Van Kerkhove explained that
“[b]ecause this is a new virus, we don’t have specific treatments for that
virus. But because this virus causes respiratory disease, those symptoms are
treated.“
“Antibiotics
won’t work against a virus,” she also emphasized.
In the
same Q&A, Dr. Van Kerkhove noted that “there are treatments that are in
development” for the new coronavirus. Over the years, she said, “many
treatments [have been] looked at to treat other coronaviruses, like the MERS
coronavirus.”
“And
hopefully, those treatments can [also] be useful for the novel coronavirus,”
she continued.
There
are currently clinical trials underway to find a treatment and a vaccine
against the MERS coronavirus, which, if successful, could lay the groundwork
for a SARS-CoV-2 vaccine and COVID-19 treatment.
Some
scientists are also experimenting with using antiretroviral therapy, which is a
treatment for HIV, against the new virus. But why might these kinds of
treatments hold any promise when it comes to fighting off this coronavirus?
According to some
studies, the combination of
antiretroviral drugs that scientists are experimenting with — lopinavir and
ritonavir — is able to attack a specialized molecule that HIV and coronaviruses
both use to replicate.
Another
allegedly promising avenue is using baricitinib — a
drug that doctors use to treat arthritis — against the new coronavirus. The
researchers who came up with this idea explain that it is likely that
SARS-CoV-2 can infect the lungs by interacting with specific receptors present
on the surface of some lung cells.
But
such receptors are also present on some cells in the kidneys, blood vessels,
and heart. Baricitinib, the researchers say, may be able to disrupt the
interaction between the virus and these key receptors. However, whether or not
it will really be effective remains to be seen.
In a
press briefing from February 5, WHO officials explained investigators’
preference for experimenting with existing drugs in fighting off the new
coronavirus.
Such
drugs, they said, have already gained official approval for use against other
specifications, meaning that they are largely safe. As a result, they need not
go through the extensive series of preclinical trials and clinical trials that
new drugs require, which can take a very long time indeed.
To get
more information about the new coronavirus outbreak and for extensive
guidelines about best practices when dealing with the virus, here are a few
international resources that you can access:
- WHO info hub
- CDC info hub
- European
Centre for Disease Prevention and Control (ECDC) info hub
- Australian
Government Department of Health resources
- BMJ latest news
- The Lancet resource center
- Nature article collection
MNT will continue to follow
any developments regarding this global health issue, and we will make sure that
we keep our readers updated and well-supplied with accurate information.
No comments:
Post a Comment