Exposure to common colds might give some people a head start in fighting COVID-19



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Larisa Labzin, The University of Queensland and Stefan Emming, The University of Queensland

Could we have some immunity to SARS-CoV-2, the virus that causes COVID-19, without ever having been exposed to it?

Some new studies found people who were never symptomatic, exposed to, or tested positive for COVID-19 have immune cells that can recognise and possibly kill virus-infected cells.

How is this possible? And what does it mean for our fight against COVID-19?

Many common colds are coronaviruses

There are seven known coronaviruses that can infect humans. Three can cause severe respiratory symptoms: SARS-CoV-2, SARS-CoV-1 (which caused the 2002-04 SARS outbreak), and MERS-CoV (which was first identified in 2012).

The other four cause relatively mild colds, and are known as the common cold coronaviruses. It’s hard to find an exact figure, but one estimate suggests up to 30% of all common colds are caused by these coronaviruses, and up to 90% of us will have some antibodies against them in our blood. Like the other viruses that cause common colds (such as rhinoviruses), they show a strong seasonality, with a wave of coronavirus infections each winter.

Immunity to these common cold coronaviruses is not very long–lasting, so we get re-infected with them all the time. We don’t know yet if our immunity to SARS-CoV-2 will also wane over time, and whether that means we could get re-infected.

A TEM image of cells under the microscope of a coronavirus disease that infects birds
Coronaviruses are a family of RNA viruses that infect humans and other animals. They are named after their crown-like spikes, derived from ‘corona’ in Latin which means ‘crown’.
CDC/Unsplash



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What did new studies find?

What these new studies did was expose some people’s blood to SARS-CoV-2. These blood samples were taken specifically from “healthy donors” – people who have never been confirmed to have coronavirus, or from whom blood was collected years before SARS-CoV-2 emerged.

Depending on the study, between 20 and 50% of these people were found to have immune cells (called T cells) that could recognise SARS-CoV-2. This is unexpected, as usually specific T cells are only present after infection with the virus.

There are two possible explanations. Either those “healthy donors” were mildly infected with SARS-CoV-2 and didn’t show symptoms or develop antibodies, but they did develop a T cell response. Or, in the case of samples taken before the disease emerged, it means these T cells can recognise multiple coronaviruses, including common colds and SARS-CoV-2.

More than just antibodies

When we get infected with a virus like SARS-CoV-2, our immune system responds in a range of ways. It generates antibodies, which can neutralise the virus to stop it entering our cells. These antibodies are specific to the virus, and thus can be used to test whether we’ve had the virus before.

But besides antibodies, we have a host of other immune weapons in our arsenal for fighting off viruses.

T cells are specialised immune cells that have lots of functions (including helping us make antibodies) but are best known for being able to recognise and kill virus-infected cells. This is really important, because if the virus has evaded antibodies and managed to get into the cells, it can start replicating. Eliminating the infected cell is one of the most efficient ways to stop the infection.

A human T cell
T cells can recognise fragments of virus across different coronaviruses, which could help our body fight COVID-19 infection.
NIAID/Wikimedia Commons



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T cells are master detectives

How do T cells know which of our body’s cells are infected with a virus? Because they can recognise small but specific snippets of viral proteins that our cells “present” on their surface. These viral snippets on the infected cell surface act like a beacon for the T cells to recognise and eliminate the virus-infected cells. Like antibodies, after the infection is cleared, we keep some of those T cells around in case we get reinfected with the same virus.

The small bits of virus presented on the infected cell’s surface can come from all parts of the virus, including the ones from inside the virus, which tend to be very similar across the different coronaviruses. That means a T cell that recognises a viral protein fragment from one type of coronavirus could potentially recognise the same fragment of viral protein that comes from a different coronavirus.

For example, if a virus was like a car, the antibody might recognise and bind to the outside, and it would only recognise a certain colour, year, and type of car.

But the T cell could recognise the specific bits, like the engine. So if the same engine was in loads of different cars, even though you might have really different cars, as long as it’s a petrol engine the T cell would recognise it. So it’s possible some of our T cells that were formed during a common cold infection are recognising SARS-CoV-2 and helping our immune system have a headstart for fighting SARS-CoV-2.

So these T cells can be cross protective — they work against different coronaviruses — and they can be very longlasting. In patients who recovered from SARS-CoV-1, specific T cells were still detectable up to 11 years later. This T cell memory could protect us from developing severe COVID-19, and could possibly explain why some people get so sick with COVID-19 while other people do not.

It’s not all rosy

While T cells represent another measure of whether people have been infected or not, we can’t use them as a quick diagnostic tool because detecting virus-specific T cells is far more slow, laborious and difficult than detecting antibodies.

We also don’t know yet what this pre-existing T cell immunity means for immune protection. We don’t even know whether the specific T cells generated during SARS-CoV-2 infection will be enough to protect us from COVID-19, and how important they are compared with the antibody responses.

Therefore, the most successful vaccines will likely induce both protective antibody and T cell responses to SARS-CoV-2.




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The Conversation


Larisa Labzin, Research Fellow, Institute for Molecular Bioscience, The University of Queensland and Stefan Emming, Postdoctoral Research Fellow, Institute for Molecular Bioscience, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

One vaccine to beat COVID, Sars, Mers and common cold – possible?



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Sheena Cruickshank, University of Manchester

SARS-CoV-2 – the virus that causes COVID-19 – belongs to the family of betacoronaviruses that cause everything from the common cold to Mers (which kills about one in three people infected). Despite causing a wide range of symptoms, these viruses all share similarities. If they’re similar enough, could one vaccine prevent infection from them all? Scientists have certainly been considering it.

Before we explore this question, though, we first need to take a detour into the fascinating anatomy of betacoronaviruses.

Betacoronaviruses are microscopic balls covered in spikes that encapsulate a central core of genetic material. The virus must infect cells in order to replicate, and to do this it must first attach to the cells.

Betacoronaviruses use their spikes to attach to cells by latching onto specific targets on the cells called receptors. Scientists from countries including the US and France have examined these spikes and discovered that they are made up of two pieces, or “domains”, imaginatively called S1 and S2.

These spike domains help the virus attach to host cells in a variety of ways. For example, the viruses that cause COVID-19 and Sars both use a part of the S1 domain called the receptor binding domain (RBD) to stick to the host cell receptor (ACE2). But the cold-causing viruses do not.

By comparing the features of the spikes between all the betacoronaviruses that cause human disease, researchers have discovered similarities and differences between them. Whereas S1 domains are quite variable between virus family members, the S2 domains are quite similar.

Similarities in virus structure are important because they can help our immune system get tricked into responding and fighting several types of closely related viruses. This happens because similar domains will have similar features that can be detected by our antibodies.

Antibodies are made by specialised white blood cells called B cells. They have several functions in infection, such as helping other white blood cells detect and kill viruses or virally infected cells. Antibodies can also stop viruses from getting into cells by blocking the cell receptors, such as ACE2 in the case of COVID-19.

However, as powerful as they are, antibodies take time to generate – it can take seven to ten days to start making protective antibodies. Once the B cells know what antibodies to make, they will remember, and if they meet the same infection again, they can react almost instantly and make even more antibodies than before. This feature is termed the memory response.

Vaccines work by trying to create immune memory by supplying the features of the virus that will trigger natural antibody production without the need for a full-blown infection. Could structural similarities between related betacoronaviruses be used to make vaccines that will generate antibodies recognising several virus family members?

Cross-reactivity

To unpick this puzzle, it is necessary to look at whether antibodies can recognise more than one type of virus, a phenomenon known as cross-reactivity. Tests like this showed that antibodies to the RBD part of the S1 domain of the spike protein that causes Sars cross-reacted with the virus that causes COVID-19.

Researchers have also found that antibodies to parts of the S2 domain of the spike protein were cross-reactive (albeit weakly) with the other betacorononaviruses in a study that has not yet been peer-reviewed. However, antibody binding is not enough to say whether a target is suitable for further development into a vaccine or drug.

These discoveries of potentially cross-reacting antibodies are exciting because they could open the door to new drugs and vaccines that tackle COVID-19. A side product could be the potential to offer some protection against future coronaviruses that we have yet to encounter.

Disease enhancement

However, a cautionary note is warranted. Although antibodies can be powerful allies in the fight against infection, they can pose serious threats to our health. Antibody-dependent enhancement (ADE) is a phenomenon that can occur when an antibody bound to a virus actually helps the viruses to enter and infect cells, including cells it could not normally infect, such as some types of white blood cell.

Once the virus gets inside the white blood cell, it hijacks the cell and effectively turns it into a Trojan horse. These Trojan horses enable the virus to hide and thrive within the cell and get spread around the body – in effect amplifying and accelerating the course of disease.

ADE is not known to occur in COVID-19 but has been observed in dengue fever. There is still much we don’t understand about ADE, but the likelihood appears to be highest when there are several variants of a particular virus circulating in a population.

Disease enhancement has been seen in dengue fever.
khlungcenter/Shutterstock

A huge question, therefore, is whether a vaccine that exploited similarities between the cold-causing viruses and COVID-19 would cause a bigger risk of ADE? Most COVID vaccine trials are focused on the RBD region of the spike protein, which does not elicit such broadly cross-reactive antibodies and, as such, are less likely to pose a risk of ADE.

Another possible risk antibodies can cause is the condition known as vaccine-associated enhanced respiratory disease (ERD). ERD occurs when high levels of antibodies bind to viruses, causing clumps of virus and antibody. The clumps can cause blockages in the small airways in the lungs with potentially devastating results. This risk, although rare and unlikely, emphasises the need for caution to ensure any vaccines and new drugs are properly tested for safety before they are widely used.

On balance, given the questions around the functionality of cross-reactive antibodies alongside the potential risks, it seems unlikely that in the near future there will be a COVID-19 vaccine that will also protect us from Sars, Mers and some types of common cold. What is clear, though, is that the more we learn about how these viruses evolve, their similarities and differences and the way our immune response reacts, the better chance we have to win the war against COVID-19.The Conversation

Sheena Cruickshank, Professor in Biomedical Sciences, University of Manchester

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Coronavirus or just a common cold? What to do when your child gets sick this winter



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Nicholas Wood, University of Sydney and Philip Britton, University of Sydney

It’s Sunday night, around 8pm, when your ten-year-old tells you she has a sore throat. She doesn’t have any other symptoms, and feels OK. You tell her “let’s see how you feel in the morning” and she happily goes off to sleep.

But you’re left wondering what you’ll do if her throat is still sore the next day — or if she’s developed other symptoms by then. Should you get her swabbed for COVID-19?

Like most Australians, you haven’t recently travelled overseas or been in contact with anyone with COVID-19. And like most kids, your children often get coughs and colds during winter.




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COVID-19 symptoms in kids resemble other respiratory infections

Generally, in their first 12 years, children can experience up to four to eight respiratory tract infections, or “colds”, per year. This number is highest among the youngest children.

One-quarter of all GP visits in children under five in Australia are for respiratory tract infections.

A recent review showed COVID-19 symptoms in children were typical of most acute respiratory infections and included fever, cough, sore throat, sneezing, muscle aches and fatigue.

In general, COVID-19 in children is less severe than in adults.

In children, the symptoms of COVID-19 might appear like the symptoms of any cold or flu.
Shutterstock

So how do I know if I should get my child tested?

If your child is unwell you can check their symptoms using healthdirect’s coronavirus symptom checker.

It will ask you questions based on what we know to be common symptoms of COVID-19, including whether you or the person you’re caring for have:

  • a fever of 37.5℃ or more; or

  • symptoms suggesting fever (such as night sweats or chills); or

  • an acute respiratory infection (for example, cough, shortness of breath, sore throat); or

  • loss of smell or taste.




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It’s possible these could also be symptoms of a different respiratory infection. But if your child is displaying any of these symptoms, the current federal government guidelines recommend they stay at home and get tested.

You can also ask your GP if you’re not sure whether your child needs a test.

How likely is it my child will test positive to COVID-19?

Although Victoria is currently experiencing a spike, Australia has largely “flattened the curve”. In the past month there have been less than 40 new cases nationally each day.

Around the country, since the pandemic began, we’ve performed more than two million tests and identified 7,521 cases.

This means fewer than 0.5% of tests have been positive. And only a small proportion of confirmed cases have been in children.

So in our current situation it’s much more likely your child’s fever or runny nose is caused by one of the common respiratory viruses, such as rhinovirus, that we see each winter.

How sustainable is all this testing?

We’re now performing more tests each day than we were at the height of the pandemic in late March.

Australia’s high level of testing has undoubtedly played a significant role in our successful response to the COVID-19 pandemic.

But we now must ask ourselves whether, with potentially diminishing returns, it’s sustainable to keep testing every child with a cold for the foreseeable future.

Let’s remember there are 4.7 million children in Australia under 15 and each of them, particularly the younger ones, are likely to get multiple respiratory infections each year.




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One of the risks of a continued emphasis on COVID-19 testing is that when a child returns a negative result, the parent thinks “all good, my child doesn’t have coronavirus, they can go back to school”.

This risks spreading non-COVID-19 viruses to others, who then develop respiratory symptoms and need to be tested. Many of these viruses spread easily among children, especially where they’re in close contact, such as in childcare centres.

This may lead to an upward spiral of respiratory infections, particularly during winter when colds and the flu are traditional foes.

Viral infections can spread easily among children.
Shutterstock

Keep sick kids at home

While testing is important, physical distancing and hygiene measures have been instrumental in flattening the curve.

And as a bonus, these measures may have led to decreased incidence of other viral infections in the community.

In our hospital in Sydney, we’ve seen fewer hospitalisations for respiratory syncytial virus this year, a common cause of infant hospitalisations.

Nationally, in the first five months of 2020 there were 20,569 influenza notifications, compared to more than 74,000 at the same point last year.




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Although restrictions are easing, Australians should continue to focus on physical distancing and hygiene throughout winter.

We need to see this pandemic as an opportunity to shift to a new normal: that is, staying at home when you’re sick, and keeping your child at home if they’re unwell (until their symptoms resolve).

We know it’s not always practical, but hopefully this “new normal” will see more flexibility from employers in these circumstances.

Finally, yes, follow public health advice around getting tested for COVID-19. But let’s not view this as the only thing that matters.The Conversation

Nicholas Wood, Associate Professor, Discipline of Childhood and Adolescent Health, University of Sydney and Philip Britton, Senior lecturer, Child and Adolescent Health, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Can you die from a common cold?



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Estrada Anton/Shutterstock

Peter Barlow, Edinburgh Napier University

Most people know that the flu can kill. Indeed, the so-called Spanish flu killed 50 million people in 1918 – more than were killed in the first world war. But what about the common cold? Can you really catch your death?

The cold is a collection of symptoms – coughing, sneezing, a runny nose, tiredness and perhaps a fever – rather than a defined disease. Although it shares a lot with the initial symptoms with the flu, it’s a very different infection.

Rhinovirus causes about half of all colds, but other viruses can cause one or more of the symptoms of a cold, including adenovirus, influenza virus, respiratory syncytial virus and parainfluenza virus.

The rhinovirus causes about half of all colds.
Maryna Olyak/Shutterstock

The common cold is normally a mild illness that resolves without treatment in a few days. And because of its mild nature, most cases are self-diagnosed. However, infection with rhinovirus or one of the other viruses responsible for common cold symptoms can be serious in some people. Complications from a cold can cause serious illnesses and, yes, even death – particularly in people who have a weak immune system.

For example, studies have shown that patients who have undergone a bone marrow transplant can have a higher likelihood of developing a serious respiratory infection. While rhinovirus is not thought to be the main cause of this, other viruses that are associated with symptoms of the common cold, such as RSV, adenovirus and parainfluenza virus, are.

There is, of course, more than one way for someone to become very sick after infection with a respiratory virus. Some viruses, such as adenovirus, can also cause symptoms throughout the body, including the gastrointestinal tract, the urinary tract and the liver.

Other viruses, like the influenza virus, can themselves potentially cause severe inflammation in the lungs, but they can also lead to particularly serious conditions, such as bacterial pneumonia.




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A virus-induced bacterial infection is one way a cold or flu virus can lead to death. While the exact mechanisms of how bacterial infections can be primed by viral infection are still being investigated, a possible way it can occur is through increased bacterial attachment to cells of the lung. For example, rhinovirus has been shown to increase the presence of a receptor called PAF-r in lung cells. This can allow bacteria, such as Streptococcus pneumoniae, to bind more effectively to the cells, increasing the likelihood of it leading to a severe condition like pneumonia.

Higher risk in some people

Unfortunately, a cold can also have more severe symptoms in the very young and the very old. Older people are more likely to develop a more serious infection compared with adults or older children. And people who smoke – or who are exposed to second-hand smoke – are also more likely to get a cold and have more severe symptoms.

Another group of people who are more severely affected by infection with cold-causing viruses are people with an existing lung condition. They can include people with asthma, cystic fibrosis or chronic obstructive pulmonary disease (COPD). Infection with a virus that causes inflammation of the airways can make breathing much harder. People with COPD who catch a mild cold virus are also at risk of developing a bacterial infection.




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While the bacterial infection in these patients can be treated with antibiotics, there is no effective antiviral treatment against all types of rhinovirus. For other respiratory viruses, such as influenza, there is an effective vaccine that can help protect vulnerable people from the flu virus, including asthmatics, the very young and the very old.

There is not one single element that dictates how severe an infection with a cold virus will be, but there are many conditions or factors that can raise a red flag.




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One of the best ways to avoid catching a cold is to wash your hands properly. This can prevent the spread of many different infections, not just the viruses that cause the common cold. And everyone, not just those classed as vulnerable, should get the flu jab. For viral infections, prevention is key.The Conversation

Peter Barlow, Professor of Immunology and Infection and Head of Research of the School of Applied Sciences, Edinburgh Napier University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Health Check: how long should you stay away when you have a cold or the flu?



File 20180722 142411 16ejslw.jpg?ixlib=rb 1.1
Symptoms of the flu generally develop more quickly and are more severe than the common cold.
By txking/Shutterstock

Nadia Charania, Auckland University of Technology

Most adults get around two to three colds a year, and children get even more. In terms of the flu, there are around 3-5 million severe cases of influenza worldwide each year and 290,000 to 650,000 deaths.

The symptoms of a cold and the flu are similar, so it’s hard to tell the difference. But the flu is usually more severe and develops more quickly than a cold.

Colds and flus can be easily passed from person to person through the air, when an infected person coughs or sneezes, and touch, when a person touches an infected surface or object like doorknobs and light switches.

So what’s the difference between colds and flus, and how long should you stay away?

Colds

Cold symptoms include a sore throat, cough, runny or stuffy nose, tiredness and headache.

Most people become contagious with cold symptoms one to two days after exposure to a cold virus. These symptoms usually peak two to four days later. The common cold usually lasts about ten days.




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There is nothing you can take to shorten the duration of a cold, and most people will get better without needing to see a doctor. But some over-the-counter medications can help alleviate the symptoms. These include anti-inflammatories (to reduce inflammation or swelling), analgesics (to reduce pain), antipyretics (to reduce fever) and decongestants (to relieve nasal congestion).

But be careful you follow the instructions and recommended dosage for these medications. A recent study of US adults who used paracetamol, the active ingredient in many cold and flu medicines, found 6.3% of users exceeded the maximum recommended daily dose. This mostly occurred during the cold and flu season.

For your own and others’ health, the best place for you to be when you’re sick is at home.
Shutterstock

Natural products such as vitamin C and echinacea are sometimes recommended to prevent and treat a cold, but there is limited evidence to support their effectiveness.

The flu

Common symptoms of the flu include fever (a temperature of 38°C or higher), cough, chills, sore throat, headache, runny or stuffy nose, tiredness and muscle aches.

An infected person can spread the flu for five to seven days after becoming infected. The infectious period can begin 24 hours before the onset of symptoms. This means you can spread the flu without even knowing you’re sick.

Influenza viruses can cause mild to severe illness in people of all ages. Most people will fully recover within one to two weeks and won’t require any medical attention. Similar to a cold, people can take some over-the-counter medications and other remedies to help alleviate symptoms.




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But some people can become acutely unwell with the flu. They may require antiviral medication and, in severe cases, hospitalisation. Those at high risk include pregnant women, children, the elderly, and people with certain medical conditions such as HIV/AIDS, asthma, diabetes and heart and lung diseases.

The flu virus strains that circulate usually change every year, so the best way to prevent getting the flu is to get the annual flu vaccine. The vaccine is moderately effective and recommended for adults and children over the age of six months. Some common side effects may occur, such as temporary soreness, redness and swelling at the injection site, fever, headache, muscle aches and nausea.

Wash with soap for at least 20 seconds to kill the germs.
Shutterstock/Alexander Raths

Avoid passing it on

If you feel unwell, stay home from work or school and rest (and get plenty of fluids) until you feel better. If you’ve had a fever, stay home for at least 24 hours after the fever has broken.

When you go back to work or school, you may still be infectious, so avoid passing the virus on by:

  • regularly washing your hands with soap and water for at least 20 seconds and drying them properly – if soap and water are not available, use an alcohol-based hand sanitiser

  • practising good cough and sneeze etiquette: cover your mouth and nose with a tissue or your upper shirtsleeve when you cough or sneeze, and throw away used tissues immediately

  • not touching your eyes, nose and mouth

  • The Conversationfrequently cleaning the surfaces and objects you’ve touched.

Nadia Charania, Senior Lecturer, Public Health, Auckland University of Technology

This article was originally published on The Conversation. Read the original article.

Health Check: should I take vitamin C or other supplements for my cold?



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Once you have a cold, taking vitamin C supplements won’t do anything.
From shutterstock.com

Clare Collins, University of Newcastle

Last week I had a shocking cold. Blocked nose, sore throat, and feeling poorly. This made me think about the countless vitamins and supplements on the market that promise to ease symptoms of a cold, help you recover faster, and reduce your chance of getting another cold.

When it comes to the common cold (also called upper respiratory tract infections) there is no magic cure (I wish) but some supplements may deliver very minor improvements. Here is what the latest research evidence says.




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Vitamin C

For the average person, taking vitamin C does not reduce the number of colds you get, or the severity of your cold.

In terms of how long your cold lasts, some studies have looked at people taking vitamin C every day, while others have focused on participants taking it once they develop a cold.

In 30 studies comparing the length of colds in people regularly taking at least 200 milligrams of vitamin C daily, there was a consistent reduction in the duration of common cold symptoms.

However, the effect was small and equates to about half a day less in adults, and half to one day less in children. These types of studies also found a very minor reduction in the amount of time needed off work or school.

Among studies where vitamin C was only started once a cold had developed, there was no difference in duration or severity of a cold.

There are some risks to taking vitamin C supplements. They can increase the risk of kidney stones in men, and shouldn’t be taken by people with the iron storage disease haemochromatosis, as vitamin C increases iron absorption.




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Special considerations

Although in the general population vitamin C has no impact on the number of colds people get, there is an exception. For people who are very physically active – such as marathon runners, skiers and soldiers exercising in very cold conditions – vitamin C halved their chance of getting a cold.

Many people take vitamin C supplements in hope it will treat their cold.
From shutterstock.com

A few studies have also found some benefit from vitamin C supplements of at least 200 milligrams a day for preventing colds among those with pneumonia.

However, taking vitamin E supplements in combination with a high intake of vitamin C from food markedly increased the risk of pneumonia.

Zinc

A review of studies testing zinc supplements in healthy adults found starting daily supplements of at least 75 milligrams within 24 hours of the onset of a cold shortened the duration by up to two days or by about one-third. It made no difference to the severity of the cold.

There was some variability in the results across trials, with insufficient evidence related to preventing colds. Researchers suggested that for some people, the side effects such as nausea or a bad taste from zinc lozenges might outweigh the benefits.

Take care to stop zinc supplements as soon as your cold resolves because taking too much zinc can trigger a copper deficiency leading to anaemia, low white blood cell count, and memory problems.

Garlic

Only one study has tested the impact of garlic on the common cold. Researchers asked 146 people to take garlic supplements or a placebo daily for 12 weeks. They then tallied the number and duration of their colds.

The group that took garlic reported fewer colds than those who took the placebo. The duration of colds was the same in both groups, but some people had an adverse reaction to the garlic, such as a rash, or found the garlic odour unpleasant.

Because there is only one trial, we need to be cautious about recommending garlic to prevent or treat colds. We also need to be cautious about interpreting the results because the colds were tracked using self-report, which could be biased.




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Probiotics

In a review of 13 trials of probiotic supplements that included more than 3,700 children, adults and older adults, those taking supplements were less likely to get a cold.

Their colds were also likely to be of shorter duration and less severe, in terms of the number of school or work days missed.

There is some evidence that probiotics, which can be found in yoghurt, may reduce the incidence of colds.
From shutterstock.com

Most supplements were milk-based products such as yoghurt. Only three studies used powders, while two used capsules.

The quality of the all the probiotic studies, however, was very poor, with bias and limitations. This means the results need to be interpreted with caution.

Echinacea

Echinacea is a group of flowering plants commonly found in North America. These days you can buy echinacea products in capsules, tablets or drops.

A review of echinacea products found they provide no benefit in treating colds. However, the authors indicated some echinacea products may possibly have a weak benefit, and further research is needed.

Chicken soup

Yep, I’ve saved the best until last.

In a novel experiment on 15 healthy adults, researchers measured the participants’ nasal mucus flow velocity – our ability to break down and expel mucus to breathe more clearly. They tested how runny participants’ noses were after sipping either hot water, hot chicken soup or cold water, or sucking them through a straw.

Sipping hot water or chicken soup made participants’ noses run more than cold water, but sipping chicken soup worked the best. The researchers attributed this to the chicken soup stimulating smell and/or taste receptors, which then increased nasal mucus flow.

Another study on chicken soup found it can help fight infection and recovery from respiratory tract infections.

The ConversationOther researchers have shown comfort foods, such as chicken soup, can help us feel better.

Clare Collins, Professor in Nutrition and Dietetics, University of Newcastle

This article was originally published on The Conversation. Read the original article.