The UK Health Security Agency (UKHSA) has issued guidance drawing attention to a widespread but frequently under-discussed virus: adenovirus. The agency states that most people in the UK are likely to have been infected by this common pathogen before they reach the age of 10.
What is Adenovirus and How Does it Spread?
Adenoviruses are a group of viruses known for causing a wide array of illnesses. Unlike seasonal flu, they are not confined to winter and can circulate year-round. The virus is highly contagious and spreads easily in environments where people are in close contact.
Common settings for transmission include schools, nurseries, and hospitals. Infection can occur through contact with contaminated surfaces or through the air when an infected person coughs or sneezes.
Recognising the Symptoms and Potential Complications
Initial symptoms of an adenovirus infection are often mild and can be mistaken for a common cold. These typically include a runny or blocked nose, sore throat, fever, and a cough.
However, the UKHSA emphasises that the virus can also lead to more specific and sometimes serious conditions, particularly in vulnerable individuals. Potential complications include:
- Gastroenteritis (a 'tummy bug')
- Ear infections
- Croup (a 'barking' cough in children)
- Bronchitis and pneumonia
- Conjunctivitis (pink eye)
Symptoms usually appear between two days and two weeks after exposure. For most healthy individuals, the infection will run its course and resolve on its own within a few days to two weeks, though severe cases may last longer.
When Should You Seek Medical Advice?
While most cases are mild, the UKHSA advises contacting a doctor if you or someone you care for shows signs of an adenovirus infection and meets certain criteria. Key warning signs include:
Red eyes, eye pain, or changes in vision. Difficulty breathing is another serious symptom that requires prompt attention. Severe diarrhoea, vomiting, or signs of dehydration also warrant medical advice.
Furthermore, a high fever lasting more than a few days is a concern. Special care should be taken for babies under three months old or anyone with a weakened immune system, as they are at greater risk of severe infection.
The agency's full guidance on adenovirus, published on 8 January 2026, remains available on the official UKHSA website for the public.
