Coronavirus: An explainer
Dr Barbara Brito Rodriguez is a Chancellor's Postdoctoral Research Fellow with The ithree Institute - Institute of Infection, Immunity and Innovation - and she takes us through what we need to know about the novel coronavirus.
What is a virus?
Most organisms, like humans, animals and even bacteria, are made of cells. They take nutrients from the environment to grow, replicate and function. Viruses, in contrast, are agents that only consist of their genetic material, protected by a protein, and some of them have more outer layers, so they are structurally much more uncomplicated than 'cellular' organisms. Viruses replicate inside a living cell that they specifically recognise. For example, respiratory viruses will most likely recognise cells in the respiratory tract to enter, but will not enter another type of cell (in most cases). Once they enter a cell, they hijack the cell's machinery to replicate and make new viruses. In this process, viruses can make a person ill and release more viruses to infect more cells and more people. However, they can also replicate or live latent inside us without causing much trouble. We live with many viruses that do not cause any illness.
What is a pandemic?
To understand the term pandemic, we need to talk about the term epidemic. An epidemic is when a disease/health issue occurs in a population in numbers higher than what is normally expected. In the case of infectious diseases (caused by bacteria or viruses) it can be that disease, like influenza, where cases are higher than expected for a typical season. In general, these types of events may be caused by new and unexpected 'strains' or 'types' of a pathogen, or from a pathogen that is completely new to humans. These are typically viruses that 'jump' from one species to another, like Ebola from bats, MERS from camels and SARS from bats/civet cat.
When this event is not only local or regional, and it spreads globally, it's called a pandemic.
What makes this coronavirus outbreak so dangerous? Is this outbreak as bad as Ebola or SARS?
It is hard to predict the dimension that this outbreak is going to reach. The Ebola outbreak was different because the case fatality (the number of infected people that died) was more than 50%. At the moment, and with preliminary information, we know that the 132 deaths from ‘2019-nCoV acute respiratory disease’ (the official name of the disease that is causing the current pandemic, and where the ‘n’ is for novel and ‘CoV’ is for coronavirus) represent less than 5% of the reported cases. Some initial investigations indicate that this outbreak resembles SARS in some aspects. The control and response at the beginning of these epidemics (the earlier, the better) will likely change its fate. Chinese authorities are taking drastic measures to contain this outbreak, and it is still early to predict if the outcome will be similar to SARS. The New England Journal of Medicine has a useful comparative table of the characteristics of swine flu, SARS, MERS, Ebola and the H7N9 bird flu.
Where did the coronavirus virus come from?
Researchers are working on sequencing viruses from different animal species in the area, and at the moment, the closest virus is one detected from bats. There is no scientific evidence of snake origins.
At the moment it is not clear if the species jump was directly from bats to humans, or if there was another species in the middle from which humans were infected.
A news article mentions that several coronaviruses have been identified and sequenced from many animal species in the Wuhan seafood market (that also had live animals for meat) associated with the first group of people affected with pneumonia and caused by this 2019-nCoV. This effort, conducted by the Chinese Center for Disease Control and Prevention (CDC), is aimed at finding the origins. However, this also means that this species' jump may repeat in the future unless there is logistic feasibility to prevent such close contact between wildlife species and humans. Nevertheless, there is still speculation that the first cases may not have been tied to the market, and that is still under investigation.
Is there a vaccine to protect humans from this virus?
Not yet, development of vaccine takes years of research and clinical trials, as well as studies involving typically thousands of people, to confirm that the vaccine is safe and effective, before it is available to the community. There are currently ongoing clinical trials for the MERS coronaviruses, that may eventually help to prevent these diseases.
The National Institutes of Health (US) announced that they are investigating a candidate vaccine for the new virus, although it will take at least a few months until the first phase of clinical trials are underway, and more than a year until a vaccine might be available.
What is the World Health Organisation (WHO) doing?
The WHO has just declared this outbreak a Public Health Emergency of International Concern (PHEIC). PHEIC is an extraordinary event that constitutes a public health risk to other States through international spread of disease, and that potentially requires a coordinated international response. The WHO and other health organisations around the globe are continually monitoring developments and supporting research and prevention. The WHO is coordinating global work on surveillance, epidemiology, modelling, diagnostics, clinical care and treatment, and other ways to identify and manage the disease and limit onward transmission. There is regular contact between the WHO and the Member States where cases have been reported to inform other countries about the situation and provide appropriate support.
What is best way to avoid catching the virus? Has the risk been overhyped?
It is hard for authorities to balance between not causing panic, while at the same time making sure that sensible ways to avoid the risk are taken. The WHO advises taking preventive measures such as washing hands, staying home if you feel sick, covering your mouth and nose when coughing and sneezing. In general, respiratory viruses are more likely to be successful in spreading during winter months. Respiratory viruses can remain infectious on surfaces or the environment for more time when temperatures are lower. However, because this is a new virus, there are still many unknowns about its ability spread, and how temperature may affect the virus. UTS is providing updated advises based on the situation and health authorities’ recommendations.
Reports say that there is sustained human to human transmission to mainland China. As of January 30th, the WHO had reported 7736 confirmed cases, 12167 suspected, 1370 severe and 170 deaths in China. There are 82 cases confirmed outside China in 18 countries. In Australia, 7 cases have been confirmed: 4 of them in New South Wales. There is no human to human transmission evidence within Australia at the moment (they all acquired the infection overseas). However, there is already one confirmed person to person in 3 countries outside China. It is advisable to keep yourself informed about the local situation, as these figures will change daily.