Flu Strain Mutates, Prompting Urgent Vaccination Calls in UK

This year’s flu season is shaping up to be particularly severe, with experts noting that a mutated strain of the virus is both more contagious and more dangerous. Health officials have described the onset of this flu season as “unusually early,” raising concerns that the UK may face one of its toughest flu seasons in recent years. The situation follows an alarming trend observed in Australia, which experienced its worst flu season on record, often serving as an early indicator for the UK.

Vaccination efforts have gained urgency, with the NHS issuing a “flu jab SOS” urging all eligible individuals to get vaccinated. The health service reported that flu cases have already tripled compared to the same period last year, and with several weeks remaining before the peak of the season, the situation is becoming critical.

Concerns Over the Dominant Strain

The dominant circulating virus this season is identified as influenza A (H3N2), which is particularly concerning due to its history of causing more severe illness. According to Dr. Antonia Ho, a Clinical Senior Lecturer and Consultant in Infectious Diseases at the University of Glasgow, “Of the two seasonal influenza A viruses, the current dominant circulating virus (A/H3N2) tends to cause more severe illness than A/H1N1, particularly in older adults.”

Statistical data from the previous winter highlights this severity; during the 2022/23 season, there were approximately 16,000 influenza-associated deaths linked to A(H3N2), compared to 8,000 deaths from the previous winter season. Dr. Ho pointed out that this year’s strain has emerged about five weeks earlier than expected, potentially leaving many vulnerable individuals without timely vaccination.

Mutation and Transmission Rates

Experts have identified that the current flu strain has acquired seven new mutations over the summer, which may allow it to evade immunity built from past infections and vaccinations. “The virus could have changed sufficiently to escape the immunity that has been built up from previous infections and vaccinations,” Dr. Ho explained. This change is reflected in the estimated reproduction number, or R value, which has reportedly increased from 1.2 to 1.4. This means that 100 infected individuals could potentially pass the virus to 140 others.

Recent data released by the UK Health Security Agency (UKHSA) on November 6, 2023, shows a significant rise in flu positivity rates, climbing to 10.9 percent, up from 8.2 percent the previous week and 6.1 percent two weeks prior. These statistics indicate a troubling trend as health authorities prepare for the peak flu season ahead.

Vaccination remains a crucial defense against the virus, particularly for individuals aged 65 and over, those under 65 in clinical risk groups, care home residents, and frontline health and social care workers. Despite these recommendations, the UKHSA has reported that less than a third, or 28.9 percent, of those with long-term health conditions have received their flu vaccine.

Ed Hutchinson, a Professor of Molecular and Cellular Virology at the University of Glasgow, emphasized the importance of vaccination this year. “The concern is that the H3N2 virus might have changed more than we expected, meaning that this component of the vaccine could be less protective than normal and cause a ‘bad flu year’,” he said. Nonetheless, he reiterated that it is vital for those eligible to receive the vaccine promptly.

The evolving situation underscores the need for public awareness and proactive health measures as the flu season progresses. With the stakes higher than usual, health officials continue to advocate for vaccination to mitigate the potential impact of this virulent strain.