Four illnesses circulating through the UK this winter have been labelled a “quad-demic”, but what is it, and how can we protect ourselves from it?

The UK Health and Security Agency (UKHSA) is currently monitoring four illnesses that are all expected to peak throughout winter.

They are flu, Covid, respiratory syncytial virus (RSV) and norovirus.

The latest weekly UKHSA figures showed that four of the three illnesses had shown an increase from the previous week, with only Covid remaining stable.

What is a ‘Quad-demic’?

Dr David Lloyd, an NHS GP, told Sky News Breakfast that the term referred to “four very common viral illnesses that circulate every winter in different peaks”.

He added that the increased time we spend in houses together and socialising over Christmas means that illness in winter happens more frequently.

He said: “This is peak time so even if you are fit and healthy, your chances of catching all of these illnesses if quite high.”

The term has emerged after the NHS warned of a tripledemic earlier this year, with flu, Covid and RSV circulating heavily during October.

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At that time, Dr Chun Tang, a GP at Pall Mall said: “A ‘tripledemic’ refers to side-by-side outbreaks of three respiratory illnesses, typically occurring during the autumn and winter seasons.

“In recent years, it’s been used to describe the simultaneous spread of COVID-19, influenza (flu), and respiratory syncytial virus (RSV).

“Each of these viruses can cause severe illness, especially in vulnerable groups like the elderly, young children, and those with weakened immune systems.”

Flu, COVID-19 and RSV symptoms

There are a number of symptoms that are the same across all three viruses (flu, COVID-19 and RSV), according to Dr Tang, including:

  • Fever
  • Cough
  • Runny nose
  • Fatigue

This can "make it difficult to tell the difference between them", the doctor added.

How to tell if you have a cold, the flu or COVID-19

Difference in symptoms

However, there are some key differences to look out for.

COVID-19

Covid, according to Dr Tang, can lead to:

  • Loss of smell or taste
  • Breathing difficulties

Other COVID-19 symptoms, according to the NHS, are:

  • Headache
  • Loss of appetite
  • Diarrhoea
  • Feeling or being sick

RSV

Dr Tang said: "RSV often causes wheezing and is more likely to affect infants."

Most people only get cold-like symptoms with RSV, the NHS adds, but it can also lead to more serious infections (such as pneumonia or bronchiolitis).

In that case it may also cause:

  • A cough that gets worse
  • Shortness of breath
  • Faster breathing or long gaps between breaths
  • Loss of appetite
  • Noisy breathing (wheezing)
  • Confusion (in older adults)

Flu

As for the flu, Dr Tang commented: "(The flu) tends to hit quickly with sudden fever and body aches."

Other flu symptoms, according to the NHS, include:

  • Difficulty sleeping
  • Sore throat
  • Headache
  • Loss of appetite
  • Diarrhoea or tummy pain
  • Feeling and being sick

There are a number of symptoms that set the flu, COVID-19 and RSV apart.There are several symptoms that set the flu, COVID-19 and RSV apart. (Image: Alamy/PA)

Dr Tang urged anyone whose symptoms become severe or worsen over time to contact their local GP, especially if you have trouble breathing, persistent high fever, confusion, or chest pain.

“For infants, seek medical attention if they are struggling to breathe, are dehydrated, or if the child becomes unusually lethargic,” he added.

Is it possible to get all viruses at the same time?

Yes, it is possible to get more than one of these viruses together, Dr Tang warned.

He said: “Being infected with multiple respiratory viruses can increase the severity of illness and make it harder for the body to recover, especially for those with weakened immune systems or existing health conditions.”

How to protect yourself against the 'quad-demic'

You can protect yourself from the 'quad-demic' by keeping up to date with available vaccines.

One of the best ways to protect yourself against the 'tripledemic' is by keeping up to date with you vaccinations.One of the best ways to protect yourself against the 'tripledemic' is by keeping up to date with you vaccinations. (Image: Alamy/PA) “There are vaccines for flu and COVID-19, and this year an RSV vaccine has been approved for older adults,” Dr Tang said.

“Vaccination is crucial for reducing the risk of severe illness.”

Eligible people can book in for a vaccination via the NHS website, the NHS App, or by calling 119 for free.

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Practicing good hygiene is also important in helping protect against the trio of viruses sweeping across the UK.

“Regular hand washing, mask-wearing in crowded places, and staying home when sick can help reduce the spread,” said Dr Tang.

Taking vitamin D supplements can also help support immune health.