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Cold, Flu or COVID? How to Tell the Difference This Winter
- Dr Ravi Gowda
- Dec 16
- 10 min read
Updated: 3 days ago
It's that time of year again. Everywhere you turn, someone's coughing, sneezing, or looking decidedly under the weather. You wake up one morning with a scratchy throat and aching muscles, and the inevitable question crosses your mind: is this just a common cold, or could it be flu? Or worse still, has COVID made an unwelcome return?
With winter respiratory illnesses circulating at high levels across the UK, knowing how to differentiate between a cold, flu and COVID has become more important than ever. This year's flu season could be one of the most severe we've seen in recent years, with the H3N2 strain causing significantly higher hospital admissions than we'd normally expect at this time of year.
In this article, we'll help you understand the key differences between these winter illnesses, explain when you should be concerned, and most importantly, discuss how you can protect yourself and your loved ones through vaccination and simple preventive measures.
We cover:
Why This Winter Feels Different
Before we get into the symptoms, it's worth understanding why this winter is particularly challenging. We're currently seeing a surge in flu cases that's outpacing previous years. In the first week of December, flu hospitalisations were significantly higher than in previous years, and current projections suggest we could see anywhere between 5,000 to 8,000 patients in hospital with flu in the coming weeks.
The dominant strain circulating this winter is H3N2, specifically a variant called subclade K. Some media outlets have dubbed it the "superflu," though that's slightly sensationalised. What makes this particular strain notable is that it's mutated in ways that reduce immune recognition compared to previous flu strains. This kind of ‘antigenic drift’ happens every winter with flu viruses, which is why we need a new vaccine each year. However, this season's changes have been significant enough that more people are getting ill and more are ending up in hospital than we'd typically expect at this point in winter.
Understanding the Common Cold
Let's start with the mildest of our winter troublemakers: the common cold.
Cold symptoms typically develop gradually over two to three days, which is one of the key ways to distinguish them from flu. You might start with a slightly scratchy throat on Monday, wake up with a blocked nose on Tuesday, and by Wednesday you're sneezing and feeling generally a bit rubbish, but you can still function.
The main symptoms of a cold include:
a blocked or runny nose
sneezing
a sore throat
a hoarse voice
a cough
You might also experience a slight temperature, though this is less common than with flu or COVID. Some people get a feeling of pressure in their ears and face, particularly if their sinuses become congested.
Here's the crucial point: symptoms of a cold usually occur gradually without causing a fever or body aches. If you're experiencing severe body aches or a high fever, you're probably not dealing with a simple cold.
Most colds are caused by rhinoviruses, and there are over 200 different viruses that can cause cold symptoms. The good news is that colds rarely have serious consequences, and most people recover on their own within seven to ten days without needing medical intervention.
Recognising the Flu
Flu is an entirely different beast, and it's important not to underestimate it. Flu is far worse than an ordinary cold, and the key distinguishing feature is the sudden onset and severity of symptoms.
With flu, you don't get a gradual build-up of symptoms. One moment you're absolutely fine, and the next, you feel like you’ve been hit by a freight train. Within one to two days of being infected, you'll suddenly develop:
a high fever
terrible aches and pains throughout your whole body
severe headaches
extreme fatigue
You'll feel absolutely dreadful. This rapid onset is one of the most reliable ways to differentiate flu from a cold.
When you have flu, you're not getting out of bed, let alone going to work. Your muscles ache, you can't think straight, and the idea of doing anything other than lying down is completely overwhelming. You might also have a dry cough, sore throat, and occasionally nausea or vomiting, though these are less common in adults than in children.
It's worth noting that over the past two winters, at least 18,000 deaths were associated with flu, which underscores just how serious this infection can be, particularly for vulnerable groups.
The good news is that if you received last year's flu vaccine, there was a 30% to 40% reduction in hospitalisation rates for adults and 70% to 75% for children. This demonstrates just how effective vaccination can be at preventing severe illness.
COVID in 2025: What to Look For
COVID symptoms have changed over time, and what we're seeing now is quite different from the early pandemic days. Many people now experience cold-like symptoms, which can make it tricky to distinguish from other respiratory infections without testing.
Current COVID symptoms typically include:
fever or chills
continuous cough
shortness of breath
tiredness
body aches
headache
sore throat
blocked nose
loss of appetite
sometimes nausea
Change in or loss of taste or smell is more frequent with COVID than with flu, though this is less common with current variants than it was during the early pandemic.
One thing that sets COVID apart is that people infected with COVID may take longer to show symptoms and may be contagious for longer periods than those with flu. This means you could be spreading the virus before you even realise you're unwell.
It's also worth noting that COVID can cause more serious complications than flu in some people. These can include acute respiratory distress syndrome (ARDS), pneumonia, blood clots, and in some cases, long COVID, where debilitating symptoms continue for months after the initial infection.
The key message here is that you cannot tell the difference between flu and COVID by symptoms alone, and testing is needed to confirm a diagnosis. If you're experiencing symptoms and you're not sure what's causing them, the best thing to do is take a lateral flow test. They're readily available at most pharmacies, and knowing whether you have COVID helps you make informed decisions about protecting others.
Cold vs flu vs COVID: Key Differences at a Glance
To make this easier to remember, here's a quick comparison:
Symptom | Common Cold | Flu | COVID-19 |
Onset | Gradual (2-3 days) | Sudden (1-2 days) | Variable |
Fever | Rare | High (usually 38°C+) | Common |
Body Aches | Mild or absent | Severe | Moderate to severe |
Fatigue | Mild | Extreme | Moderate to severe |
Headache | Mild | Severe | Common |
Cough | Mild | Dry, can be severe | Common, persistent |
Sore Throat | Common | Sometimes | Sometimes |
Runny/Stuffy Nose | Very common | Sometimes | Sometimes |
Loss of Taste/Smell | Rare | Rare | More common (but less with current variants) |
Can You Function? | Yes, though uncomfortable | No, bedridden | Variable |
Common Cold: You can usually still function and go about your day, though you won't be at your best.
Flu: You'll be completely knocked out and unable to function normally. The severity and sudden onset are what distinguish it from a cold.
COVID: Symptoms can vary widely from person to person. Testing is essential for accurate diagnosis as symptoms alone cannot reliably distinguish it from flu.
Who Should Get the Flu Vaccine?
Given the severity of this year's flu season, vaccination has never been more important.
The NHS provides free flu vaccines to people who are most at risk of serious complications. This includes:
Everyone aged 65 and over
Pregnant women at any stage of pregnancy
Children aged 2 to 17 years
Anyone with certain long-term health conditions (such as asthma requiring regular inhalers, COPD, heart disease, diabetes, weakened immune systems, or neurological conditions)
Carers and those living with someone who's immunocompromised
Frontline health and social care workers
If you haven't been contacted about your flu jab yet and you think you're eligible, get in touch with your GP surgery or local pharmacy.
Should Healthy Adults Get Vaccinated?
This is a question I'm asked frequently, and my answer is always the same: absolutely, yes.
Even if you're young, fit, and healthy, flu can still knock you sideways. During the 2024 to 2025 season in the UK, 53 children under 18 years died from flu-related complications, a 56% increase from the previous season's 34 deaths. Many of these children had no underlying health conditions whatsoever. Flu doesn't discriminate, and anyone can develop serious complications.
Beyond protecting yourself, there's another crucial reason to get vaccinated: protecting the vulnerable people around you. When you get vaccinated, you're not just reducing your own risk of getting ill, you're also helping to protect your elderly parents, your friends with health conditions, and young babies who can't yet be vaccinated themselves.
If you're not eligible for a free NHS vaccine, you can still get one privately. At Health Klinix, we offer the flu vaccine for around £21, and crucially, we provide the cell-based vaccine. This is important because the cheaper egg-based vaccines that some places offer may not work as well against the H3N2 strain we're currently seeing. The cell-based vaccine is more closely matched to the circulating virus, which means you're getting better protection for your money.
How Effective Is the Flu Vaccine?
I’m going to be honest about this. The flu vaccine isn't perfect. Depending on the season and how well-matched it is to circulating strains, it's typically around 30% to 70% effective at preventing infection.
But here's what really matters: even if you do catch flu after being vaccinated, your illness is likely to be much milder. You're far less likely to end up in hospital, and you're far less likely to develop serious complications like pneumonia. The vaccine significantly reduces your risk of severe disease, and that's what we care about most from a medical perspective.
For children, the vaccine showed around 70% to 75% effectiveness at preventing hospital attendance, which is remarkably effective. For adults, there was approximately 30% to 40% effectiveness. When you consider the minimal risk of vaccination versus the potential for severe illness, the choice is clear.
Should You Wear a Face Mask?
The UK government hasn't made face masks mandatory, but as a consultant physician in infectious diseases, I do have a professional opinion on this.
If you have flu symptoms, or if you're caring for someone who might have flu, wearing a face mask is a sensible and considerate thing to do. Think about it logically: flu spreads through respiratory droplets when you cough or sneeze. A mask significantly reduces how much virus you're spraying into the air around you.
This is particularly important in crowded places like public transport, shops, or healthcare settings. Some hospitals have even reintroduced mask requirements in certain areas, particularly where vulnerable patients are being treated.
It's not about fear or panic. It's about being considerate and preventing transmission to people who might be more vulnerable than you are.
Other Ways to Protect Yourself
Beyond vaccination and masks, the basics still matter enormously.
Wash your hands frequently with soap and water, especially after being out in public or touching shared surfaces. If you can't wash your hands immediately, use hand sanitiser containing at least 70% alcohol.
When you cough or sneeze, always use a tissue and bin it immediately. The old advice about catching coughs and sneezes in tissues is as relevant as ever. If you don't have a tissue to hand, cough or sneeze into your elbow, not your hands, and definitely not into other people's faces.
If you're feeling unwell, please stay at home. I know it's tempting to push through and go to work anyway, particularly if you're worried about letting colleagues down or missing important meetings. But you're just going to spread illness to everyone around you, and you'll recover faster if you rest properly.
When Should You Seek Medical Advice?
Most colds, and even many cases of flu and COVID, can be managed at home with rest, fluids, and over-the-counter medications like paracetamol or ibuprofen to manage fever and aches.
However, you should seek medical advice if you experience any of the following:
difficulty breathing or shortness of breath
chest pain or pressure
persistent high fever that doesn't respond to medication
severe weakness or dizziness
confusion or difficulty staying awake
symptoms that improve and then suddenly worsen
you have underlying health conditions that put you at higher risk
For children, warning signs include:
difficulty breathing
persistent high fever
inability to keep fluids down
severe irritability or listlessness
they're simply not improving as you'd expect
If you're concerned about your symptoms or those of a family member, don't hesitate to contact your GP or call NHS 111 for advice. It's always better to check and be reassured than to wait and risk complications.
Protect Yourself This Winter
With this year's particularly severe flu season, taking preventive action has never been more important. The flu vaccine remains our best defence against serious illness, hospitalisation, and potentially life-threatening complications.
At Health Klinix, we're here to provide expert, trusted advice tailored to your individual circumstances. Our team of healthcare professionals can assess your needs and recommend the most appropriate vaccinations and preventive measures for you and your family.
Don't wait until you're already ill to think about protection. The flu vaccine is available now, and it takes about two weeks to build full immunity after vaccination, so the sooner you act, the better protected you'll be.
If you're unsure about whether the flu vaccine is right for you, or if you'd like to book your vaccination, contact Health Klinix today. Our cell-based flu vaccine offers superior protection against this year's circulating H3N2 strain, and at £21.75, it's an investment in your health and the health of those around you.
You can reach us at hello@healthklinix.co.uk or call 024 7601 6519 to book your appointment. Our clinic is located at Earlsdon Medical Centre, 77c Moor Street, Earlsdon, Coventry, CV5 6EU.
References
UK Health Security Agency. Flu vaccine providing important protection despite new subclade. GOV.UK. November 2025. Available at: https://www.gov.uk/government/news/flu-vaccine-providing-important-protection-despite-new-subclade
Whitaker H, Findlay B, Zitha J, et al. Interim 2023/2024 Season Influenza Vaccine Effectiveness in Primary and Secondary Care in the United Kingdom. Influenza and other Respiratory Viruses. 2024;18(5):e13284. Available at: https://doi.org/10.1111/irv.13284
UK Health Security Agency. Influenza in the UK, annual epidemiological report: winter 2024 to 2025. May 2025. Available at: https://www.gov.uk/government/statistics/influenza-in-the-uk-annual-epidemiological-report-winter-2024-to-2025/influenza-in-the-uk-annual-epidemiological-report-winter-2024-to-2025
NHS England. Flu and COVID-19 Seasonal Vaccination Programme: autumn/winter 2025/26. Available at: https://www.england.nhs.uk/long-read/flu-and-covid-19-seasonal-vaccination-programme-autumn-winter-2025-26/
UK Health Security Agency. Your guide to who's eligible for the autumn 2025 flu vaccine. UKHSA Blog. September 2025. Available at: https://ukhsa.blog.gov.uk/2025/09/01/your-guide-to-whos-eligible-for-the-autumn-2025-flu-vaccine/
Centers for Disease Control and Prevention. Similarities and Differences between Flu and COVID-19. Updated September 2024. Available at: https://www.cdc.gov/flu/symptoms/flu-vs-covid19.htm
About the Author
Dr Ravi Gowda is a Consultant Physician in General Internal Medicine and Infectious Diseases, and Medical Director at Health Klinix. He holds qualifications including MBBS, MRCP(UK), DTM&H, MRCGP, DCH, DRCOG, and DFFP. Dr Gowda specialises in the diagnosis and management of infectious diseases and provides expert advice on travel health and vaccination.
Disclaimer: The advice provided in this article has been written and approved by Dr Ravi Gowda. The information is for educational purposes only, and we always recommend getting direct medical advice from your doctor or a qualified clinician for your specific situation.