Health authorities have noted the H1N1 subtype appears to have undergone minor genetic drift from the strain used in vaccine production, although Professor Ho stated it remains premature to assess whether this will affect vaccine efficacy.The vaccination campaign across England has already reached 3.9 million individuals since its launch at the start of last month. Pregnant women, toddlers and school-age children became eligible for jabs from 1 September, whilst those aged over 65 and other at-risk adults gained access from October 1.Evidence from the previous winter demonstrates the programme’s effectiveness, with UKHSA estimates indicating it prevented approximately 100,000 hospital admissions and 7,000 deaths.Professor Sir Andrew Pollard, director of the Oxford Vaccine Group, stated: “There is one simple action for all those who are at risk because of age or their underlying health conditions, which is to get vaccinated as soon as possible and before we reach the peak of transmission.”