Knowns and unknowns about the new coronavirus

Didier Trono, a professor at EPFL’s Laboratory of Virology and Genetics, answers some common questions about SARS CoV-2 and the disease it causes, COVID-19.
There are a lot of things we don’t know about the new coronavirus. © Alain Herzog

We know that the new coronavirus can cause lung infections that can be fatal for elderly people and those already suffering from heart disease, respiratory problems or weakened immune systems. We also know that one of the best things we can do to protect ourselves is to wash our hands. But there are some things we don’t know – which makes it hard to predict how the pandemic will play out. We spoke with Didier Trono, a professor at EPFL’s Laboratory of Virology and Genetics, to get expert answers to some of our questions about SARS-CoV-2 (the new coronavirus) and COVID-19, the disease it causes.

How does SARS-CoV-2 work?

The virus enters the body through the respiratory system. It then multiplies in the lungs, which is why the symptoms are similar to those of pneumonia. For now, the virus doesn’t seem to affect any other parts of the body.

What are the symptoms of COVID-19?

It’s a lot like the flu – a fever and a cough. Cold-like symptoms are less common. The illness can come on strong but generally doesn’t last long. However, some people can develop a severe lung infection that results in serious complications. That’s because the infected lungs are less able to transfer oxygen to the blood, meaning the body’s cells have less of the oxygen they need to generate energy. Elderly people and those suffering from cardiac or respiratory diseases or a weakened immune system are the most at risk.

How does the virus spread?

The virus spreads mainly through droplets, especially those that come out of our mouths when we cough. These droplets can travel one, two or even three meters. The virus generally doesn’t go far from infected individuals. However, if you touch a door handle that has been contaminated, for instance, and then touch your face, you could catch the virus. Transmission of the virus is lower where clear symptoms are not present, but we can’t completely rule it out. It does not spread significantly through ventilation systems.

How widespread is the disease?

We don’t know exactly how many people are infected, since that would require performing serological tests on large numbers of people to see if they’ve developed specific antibodies, which are signatures that appear following an infection. The figures currently being reported are based on whether the virus has been detected, but the actual infection rate is certainly much higher.

Could someone become immune to SARS-CoV-2?

It appears that people develop an effective immunity after being infected. We suspect that a previous infection by another coronavirus, like one of the ones that cause the common cold in children, provide some protection against COVID-19; indeed young people, even if they are not protected against infection, do not develop serious symptoms in most cases.

How long will it take to develop a vaccine?

Scientists are working on it, but it’ll probably take 12–18 months. We currently don’t have an active antiviral treatment against COVID-19. Doctors treat it like pneumonia, with intubation if necessary.

Will the virus become less active over the summer?

Summer weather does seem to slow the propagation of seasonal influenza, which pretty much disappears in the late spring or early summer for reasons that scientists don’t fully understand. Right now it’s too soon to say whether the same will hold true for the new coronavirus.