Norovirus Warning: UK Faces Persistent High Cases and Potential Summer Wave

Norovirus in the UK: Persistently High Levels and Second Wave Concerns

The United Kingdom has been experiencing unusually high levels of norovirus activity for this time of year. Recent data indicates that laboratory-confirmed cases remain significantly above the five-season average, raising concerns among health officials.  

Key Facts:

• Stubbornly High Levels: Despite the typical seasonal decline expected with warmer weather, norovirus cases in the UK have remained "stubbornly high" in April 2025.

• Record Hospital Cases: In the week ending March 23, 2025, hospital patients with norovirus in England reached 903, which is over 60% higher than the previous record for this time of year. While this was a decrease from the mid-February peak, the decline has slowed.  

• UKHSA Warning: The UK Health Security Agency (UKHSA) has warned of a potential second wave of norovirus this summer due to a shift in circulating strains.  

• Strain Shift: Initially, the GII.17 genotype was dominant. However, a different, commonly seen genotype (GII.4) is now increasing. This means individuals who contracted norovirus earlier in the season with the GII.17 strain could be susceptible to reinfection with the GII.4 strain.

• Impact on Healthcare Settings: The high levels of norovirus are significantly impacting hospitals and care homes, with the highest rates observed in individuals aged 65 and over.  

• Symptoms: Norovirus typically causes nausea, vomiting, diarrhea, stomach pain, and sometimes a high temperature, headache, and aching limbs. Dehydration is a significant concern, especially for young children, older adults, and those with weakened immune systems.  

• Transmission: Norovirus is highly contagious and spreads easily through close contact with infected individuals, touching contaminated surfaces, and consuming contaminated food or water.  
• Hygiene Measures: Effective prevention measures include frequent and thorough handwashing with soap and warm water (alcohol gels are not as effective against norovirus), and cleaning surfaces with bleach-based products. Individuals experiencing symptoms should avoid visiting hospitals and care homes and should not return to work, school, or nursery until 48 hours after their symptoms have stopped.  

Potential Second Wave:

The emergence and increasing prevalence of the GII.4 strain, alongside the already high levels of the GII.17 strain, have led the UKHSA to warn that people could become infected with norovirus more than once this season. This potential "second wave" could place further strain on healthcare services.

Current Situation:

As of early April 2025, norovirus levels remain higher than typically seen at this time of year in the UK. Health officials are closely monitoring the situation and emphasizing the importance of hygiene practices to limit the spread of the virus.