Having a cold could help to fight off the flu because it jumpstarts the body’s antiviral defences, according to Yale University researchers.
Rhinoviruses, the most frequent cause of common colds, may be able to prevent the flu virus from infecting airways because they trigger the same immune response.
When looking at health records from more than 13,000 people the scientists noticed that people who had colds never had the flu at the same time.
Flu causes similar symptoms to a cold but is usually worse and can leave people bed-ridden with fever, aches and pains and exhaustion, while colds tend to cause coughs and sniffles but are not debilitating.
Both are caused by viruses that infect the airways – the cells in the nose, mouth and lungs.
And they are both fought off by similar mechanisms, the Yale researchers said, meaning that having one of them can stop the other one getting into the body.
Having a cold could help to fight off the flu because it jumpstarts the body’s antiviral defences, according to Yale researchers (stock photo)
Dr Foxman, assistant professor of laboratory medicine and immunobiology and senior author of the study, said: ‘When we looked at the data, it became clear that very few people had both viruses at the same time.’
She stressed that scientists do not know whether the annual seasonal spread of the common cold virus will have a similar impact on infection rates of those exposed to the coronavirus that causes Covid-19.
‘It is impossible to predict how two viruses will interact without doing the research,’ she said.
DO COLDS BUILD UP IMMUNITY AGAINST CORONAVIRUS?
A growing body of research has suggested that people may already have immunity against they have had similar illnesses in the past.
Experts have noticed the infection looks extremely similar to other, milder strains of coronaviruses which cause coughs and colds and circulate regularly.
Those who have had these in the past may have some level of ‘cross-protection’, which means they aren’t seriously harmed by Covid-19.
While it remains unlikely that people will be totally protected from any infection at all, ‘background’ immunity could make their illness less severe and death less likely.
Theories that even exposure to common colds may protect people from the coronavirus have been floating around for months.
There are four other types of coronavirus known to infect humans regularly, which are named NL63, 229E, OC43, and HKU1.
The fifth, known as SARS-CoV-2, is the one that causes Covid-19.
If people have had these in the past, their bodies may have developed some immunity to coronaviruses, an Oxford University study suggested in July.
The way cross-protection might develop lies in the fact that coronaviruses all have similar structures – that is, they have spike-shaped proteins on the outside.
These spikes may look similar to the body’s immune system and be recognised as a threat even if someone has not been infected with that particular one before.
When the body recognises a protein as a danger it can stoke the immune system into life and immediately send white blood cells and antibodies to destroy the viruses, thereby either preventing illness or making it less severe.
The body stores memories of how to fight viruses it has seen in the past and, if it encounters one that looks a lot like another one it has attacked, it may attack that more quickly than usual, too.
Immune cells are highly specific and only attack the bugs they are designed to, but if coronaviruses are extremely similar there is a chance that immunity developed to one virus may be compatible with another.
While this might not stop infection completely, the fast immune response could make the illness less severe and make it more likely that people will survive.
To test how the rhinovirus and the influenza virus interact, Dr Foxman’s lab created human airway tissue from stem cells that give rise to epithelial cells, which line the airways of the lung and are a chief target of respiratory viruses.
They found that after the tissue had been exposed to rhinovirus, the influenza virus was unable to infect the tissue.
‘The antiviral defenses were already turned on before the flu virus arrived,’ she said.
The presence of rhinovirus triggered production of the antiviral agent interferon, which is part of the early immune system response to invasion of pathogens, Dr Foxman said.
‘The effect lasted for at least five days,’ she added.
The study found the presence of rhinovirus triggered production of the antiviral agent interferon, which is part of the early immune system response to invasion of pathogens.
Dr Foxman said her lab has begun to study whether introduction of the cold virus before infection by the Covid-19 virus offers a similar type of protection.
It comes after Boris Johnson warned on Wednesday there is going to be ‘more of this wretched Covid still to come’ as he convened his Cabinet and told ministers ‘bit by bit’ the UK is ‘getting back on its feet’.
The Prime Minister told his top team that ‘we know there will be more outbreaks’ but he is ‘absolutely confident’ the Government will be able to deal with them.
One of medics’ top concerns is that a surge in coronavirus infections will coincide with flu season this winter.
The flu lands thousands of elderly people in hospital every year and puts pressure on wards and emergency units.
In a bid to prevent this, the Government is planning the biggest ever flu vaccination drive this weekend and said it hopes to immunise 30million people against the illness.
A flu jab won’t offer any protection from Covid-19 but it could reduce pressure on hospitals by stopping people catching flu.
But the number of vulnerable people getting free flu jabs in England is at an eight-year low.
Last winter just 45 per cent of people under 65 with serious health conditions, who are offered the vaccine for free on the NHS, received the jab.
This has tumbled from a peak of 52.3 per cent in the winter of 2013 and is the worst uptake since Public Health England’s records began in 2012.
This year’s vaccination programme is pledging to offer jabs to everyone over the age of 50, and 11-year-olds.
Officials hope that covering more of the at-risk groups with a flu jab will mean fewer people get seriously ill with the winter virus, which will relieve pressure on hospitals that are expected to face a resurgence of Covid-19 cases.
But getting vaccinated against the flu is not compulsory and more than half of vulnerable adults currently do not take up the offer.
Coverage is better among the elderly, around three-quarters of whom get the vaccine, but the NHS also recommends it for pregnant women, diabetics, those with serious illnesses like heart disease, children and severely overweight people.