A pharmacist shares why exactly Brits are experiencing a new ‘mystery illness’ right after the dreaded ‘super flu’ as people across the country start 2026 sick in bed
Tahira Ali and Vita Molyneux
14:01, 02 Jan 2026
“Mystery virus” has been named as this common strain of respiratory virus.(Image: Getty Images)
The festive season began with colds across Britain and a viral flu that spread nationwide – but the seasonal illnesses aren’t over. Sadly, with the new year comes news of a “mystery virus,” which causes a runny nose, coughing, sneezing and issues with the stomach.
If you’ve found yourself feeling under the weather again – even just after having the dreaded ‘super flu’ – you could be suffering from Adenovirus. Ian Budd, a pharmacist at Chemist4U, spoke to the Mirror to explain how the bug has so easily spread. He shared that the “throat/respiratory bug lines up with what clinicians and public health bodies are seeing”.
Explaining that the “mystery” illness is likely a strain of common respiratory viruses, Budd said that Adenovirus seems to have spiked given the mass of people experiencing its symptoms and visiting the GP. Insisting that the virus was not new, the pharmacist added that, “compared to a cold, Adenovirus can be more likely to cause fever and conjunctivitis, and symptoms can last longer”. Here’s everything you need to know…
READ MORE: Chickenpox vaccine rolled out on NHS TODAY – everything you need to knowREAD MORE: Snow blankets UK as Met Office warn arctic freeze could last into next week
Many Brits are welcoming in the new year with a widespread “mystery virus” affecting the respiratory system.(Image: Getty Images)How it spreads
Spread from one contagious person to another, Adenovirus has managed to circulate so widely due to a number of reasons, including close physical contact and germs travelling through the air.
This could be due to someone openly coughing or sneezing around you; the shaking of hands; the transferring of the virus from an object or surface which you may have touched, and then, with the same hand, touched your mouth, nose, or eyes before the chance to wash your hands.
Significantly, the cdc.gov website states that infection can also occur via water, noting swimming pools lacking substantial chlorine and even lakes as a potential method – though the site adds this is much less likely. Parents and carers have also been warned that Adenovirus can be caught from contact with an infected person’s excrement, highlighting nappy changes as another means of catching the horrible bug.
The first symptoms may resemble that of the common cold or flu(Image: Getty Images)Why have people caught it straight after the winter flu?
You may be wondering why are Brits catching the virus now, after experiencing the worst of the annual winter flu – and there’s one simple reason. The festive period and flu outbreak has led to many more people locked away indoors. This, along with the Christmas period, has meant more close proximity to those who may be sick, or still carry the virus.
Budd claimed that, “with COVID-19 restrictions lifted, and fewer people catching other viruses over the past few years, immunity in the community may be lower, leading to people becoming more susceptible”. The “shedding” of the virus to others can occur long after a sufferer has recovered from symptoms, especially between those with weaker immune systems.
Symptoms
Adenovirus causes a range of symptoms, many of which mirror the common cold and flu. These include:
feversore throatacute bronchitis (inflammation of the lung airways or “chest cold”)pneumonia (infection in the lungs)pink eye (conjunctivitis)acute gastroenteritis (inflammation of the stomach or intestines causing vomiting, nausea, diarrhoea and stomach pain)
The lesser known symptoms are inflammation or infection in the bladder and even neurologic disease (which affect the brain and spinal cord), though these are much less common.