Coronavirus: What scientists know so far about the virus behind the Covid-19 crisis

Severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2, is the virus that causes coronavirus disease, or Covid-19. Photo / AP

Scientists are quickly building a picture of what's driving the emerging Covid-19 pandemic – and crucially, what might happen over coming months. Science reporter Jamie Morton puts some questions to Dr Jemma Geoghegan, a senior lecturer in the University of Otago's Department of Microbiology and Immunology.

Q & A

What do we know about the virus behind the global crisis?

Severe acute respiratory syndrome coronavirus 2, or Sars-CoV-2, is the virus that causes coronavirus disease, or Covid-19. It comes from a family of viruses called the Coronaviridae.

There are many coronaviruses that infect humans already, which typically cause common colds. Two other members have caused more deadly outbreaks though: Sars-CoV and Mers-CoV.

This new coronavirus got its name because it is similar to Sars-CoV.

What's the working theory about where it came from? Although nothing seems to have been confirmed, there are suspicions it may have come from horseshoe bats, which share much of the same genetic material.

Many bats, including horseshoe bats, do contain viruses that are similar to Sars-CoV-2.

However, because every animal species hasn't been tested, we are not sure which is really the reservoir for this virus.

Many more animal surveys need to be conducted before we can determine its most likely origin.

We're told it's rare for animal coronaviruses that infect animals to go on to infect and spread between people. When it has in the past – as with Middle East Respiratory Syndrome (Mers) and Severe Acute Respiratory Syndrome (Sars) – the consequences have sometimes been serious. What does it actually take for this leap to happen?

Although it might not seem like it, it is relatively rare for any virus to jump species boundaries and go on to infect humans, let alone be able to spread person to person.

That is because a perfect combination of the right genomic and ecological factors need to align before a jump like this can happen in the first place. And we still have a very limited understand of what those factors are.

Another new study has suggested there may be two strains of the virus infecting people around the globe. What does this mean? Has the virus mutated?

A recent article has suggested that there are two "major types" - they have termed them L and S - of the virus circulating in this outbreak and that they have different rates of transmission.

This conclusion is based on two mutations in the genome between these so-called "types".

There are actually more than 100 mutations in the virus's genome that have been identified during this outbreak so far and there is no evidence any of them have led to changes in the way the virus behaves or transmits between people.

Much more experimental work is required to draw these conclusions.

Based on what we've seen in Sars and Mers, what might we expect with the evolution of this virus over weeks, months and years to come? What are the likelihoods and scenarios?

With both Sars-CoV and Mers-CoV, the case fatality rates were much higher than what we are seeing with Sars-CoV-2. In fact, many cases have been reported to be mild or even asymptomatic.

That means the virus can be transmitted and spread very easily, and it is much more difficult to contain.

It might be the case that Sars-CoV-2 will eventually become endemic meaning that, much like the flu, it will continually circulate between humans.

What makes this emerging pandemic a stand-out from others of the last century?

This is an unprecedented emerging pandemic.

The world is much more connected now compared to when previous pandemics with comparable fatality rates took place.

That being said, with access to healthcare and the sharing of data and resources, we are in a much better position now compared to when the 1918/1919 flu pandemic happened, for example.