⚠️ Flu Season Warning: UK Flu Cases Are Now Surging — Dominated by a Drifted H3N2 Strain

The UK flu season has begun much earlier and much faster than usual, and cases are now surging across the country. The UK Health Security Agency (UKHSA) confirms that the dominant strain this year is a drifted influenza A(H3N2) variant (sub-clade K). This strain now accounts for the vast majority of flu cases in people tested.

🔥 Why this flu season is different

• Almost all flu cases are influenza A, and around 84% of typed cases are H3N2.
  This pattern is consistent across community, GP and hospital surveillance.

• The H3N2 strain circulating is genetically drifted, meaning it has evolved away somewhat from the reference vaccine strain.
  UKHSA has publicly confirmed this drift.

• This increases the risk of infection spreading rapidly — which is exactly what is happening now.

🛡️ Does the flu vaccine still work?

Yes — despite the drift, UKHSA reports that the 2025–26 flu vaccine still provides important protection, including:

• ~70–75% effectiveness in children

• ~30–40% effectiveness in adults

This means vaccination dramatically reduces severity, even if it does not fully prevent infection.

⚠️ Why this matters for people with lung conditions

If you have:

• ABPA (Allergic Bronchopulmonary Aspergillosis)

• Bronchiectasis

• Asthma

• Chronic lung disease
  …you are at higher risk of:

• pneumonia

• severe chest infections

• hospitalisation

• long recovery times

H3N2 seasons are historically worse for adults and people with underlying respiratory disease.

🔺 What you should do now

1. Get vaccinated immediately

If you haven’t had your flu jab yet, do not wait.
The season is already surging and accelerating earlier than usual.

2. Be extremely cautious in high-risk environments

• Schools

• Public transport

• Healthcare settings

• Large indoor gatherings

• Poorly ventilated rooms

3. Use winter protection behaviours

• Ventilate indoor spaces

• Consider wearing a mask in crowded indoor areas

• Wash hands frequently

• Avoid contact with people who are unwell

4. If you become ill — act fast

For anyone with ABPA, bronchiectasis or asthma:

• A sudden fever

• A sharp rise in cough

• Change in sputum

• Chest tightness

• Breathing changes

…should be treated as early warning signs.
Contact your GP or respiratory team quickly, as secondary pneumonia is more likely in H3N2 seasons.

Summary

Flu is now surging across the UK, driven by a drifted H3N2 strain, and people with underlying lung disease should take this season particularly seriously.
Vaccination remains strongly protective, but additional precautions are vital during this rapid upswing in cases.