How a cold could help ward off Covid-19: Rhinovirus can jump-start body's antiviral defences and equip immune system to ward off other illness, scientists say

Suffering a common cold could provide protection against contracting Covid, scientists believe.

Experts at Yale University in the US have found that coming under attack from rhinovirus - the most frequent cause of common cold - jump-starts the body's antiviral defences, equipping the immune system to ward off other viruses. 

They are now investigating whether it does the same against coronavirus.

The body fights off rhinovirus by producing interferon. 

Previously scientists were not sure whether interferon produced in response to one virus would recognise another but the Yale study suggests exposure to rhinovirus created an immune response against flu, suggesting it would protect against other viruses.

Experts at Yale University believe that suffering from a common cold could provide protection against contracting the Covid-19 virus (file photo)

They are now looking at whether introduction of the cold virus before infection by the Covid-19 virus offers similar protection. 

Dr Ellen Foxman, of the Yale School of Medicine, said that interferon defences work only early in infection so may be used as 'a way of temporarily protecting people who are at high risk'.

Dr Foxman said: 'The common cold virus triggers the normal antiviral defences of these cells that form the lining of the airway.

'So the cells that form the lining of the airway is where all these viruses need to go to grow.

'That includes flu, common cold, Covid-19 - basically all the viruses that you get by breathing them in, they all grow in this tissue that forms the lining of your airway.'

She added: 'This response, the interferon response, which is this general defence mechanism against all viruses, we know that response does work against Covid-19.

'If you do the experiment in a lab, you can apply this chemical - interferon - to cells, then you can block the virus that causes Covid-19 as well.

'So it's possible that we'll see the same thing, but we're just beginning to do the experiments.

'Sometimes you see unexpected things happening so you have to just do the experiment and see what the result is and that that's just a work in progress at the moment.'

Dr Foxman said she thought interferon-based immunity lasted about a week, maybe up to two, adding that it did not prevent infection forever.

But she explained it may provide a 'temporary buffer against getting another virus' while the body is all 'revved up' to fight it.

Scientists found that rhinovirus, the most frequent cause of common cold, jump-starts the body's antiviral defences, equipping the immune system to ward off other viruses (file photo)

However, the expert said while she was sure this could be applied to flu, Covid-19 is unpredictable.

'One unpredictable thing is the entry receptor that Covid-19 uses to get inside your body - there have been some reports that can be increased by interferon.

'So, we just have to test how important is that, compared to having these antiviral defences at the ready,' Dr Foxman said.

She said interferon defences can be very potent against a lot of viruses, but that they only work early in infection as they stop the virus from growing.

Dr Foxman said interferons are already used as antiviral treatments for other conditions, and trials looking at their use in combating Covid-19 indicate that if given early enough in infection, there may be some benefit.

She added: 'Maybe we can think harder about just triggering this general response as a way of temporarily protecting people who are at high risk - who are in high risk of being exposed.' 

She warned that interferon response triggers a lot of the same symptoms as a cold, by added: 'When you're talking about preventing a more serious virus maybe it does make sense.'