Published 14:44 31 Dec 2025 GMT

'Mystery virus' that infected 'everyone' over Christmas finally explained

One health expert shed some light on what the virus is that has been making us all ill

Rikki Loftus

A ‘mystery virus’ that has infected ‘everyone’ over the Christmas period has finally been explained.

This comes as one health expert shed some light on what the virus is that has been making us all ill.

While it might be the most wonderful time of year, it also appears to be the time to catch a dreaded bug.

Everyone from friends, family and people at work, all seem to be coming down with cold-like symptoms including coughing, sneezing and a runny nose.

While some symptoms might last up to two weeks, the illness shouldn’t hinder you for long.

This is according to Ian Budd, who is a lead prescribing pharmacist at Chemist4U, and has explained what is most likely going on.

He said: “What we’re seeing in the news, often called a ‘mystery virus’ or a fast-spreading throat/respiratory bug, lines up with what clinicians and public health bodies are seeing: adenovirus, a group of common respiratory viruses that circulate widely.”

What is an adenovirus?

According to Public Health Scotland, adenoviruses 'can cause a wide range of illnesses such as common cold or flu-like symptoms'.

“Although human disease may often be mild or moderate, it can be severe especially when untreated in elderly or immunocompromised individuals,” the health service notes.

While these viruses 'aren’t new', Budd says that 'more people are noticing symptoms and heading to their GP'.

What is the difference between an adenovirus and a cold or flu?

“Compared to a cold, adenovirus can be more likely to cause fever and conjunctivitis, and symptoms can last longer,” Budd explained.

The difference with flu, however, is that there is currently no vaccine for adenovirus.

Due to the cold, more people are getting ill because they're spending more time indoors and are in closer proximity to people who might be carrying a bug.

Budd explained: “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.

“Adenovirus isn’t a new virus; it’s just showing up more often alongside other winter bugs.”