GPs saw fewer patients with influenza-like symptoms and hospitals had fewer respiratory emergency attendances in areas where schoolchildren received the Fluenz nasal spray flu vaccine last winter, the study by Public Health England (PHE) found.
However, differences between pilot and control areas were not statistically significant amid low levels of flu nationally last winter and a lack of data from pilot areas. Researchers said more evidence would be needed to support further roll-out.
Nevertheless, public health officials welcomed the early results as 'encouraging', with almost 53% of children in the pilot regions receiving the vaccine.
Dr Richard Pebody, study author and flu expert at PHE, said: 'Despite this season being of relatively low intensity, these early findings already suggest a likely impact of vaccinating school-age children on levels of circulating flu, which is encouraging for the ongoing roll-out.
'It will be important we continue this ongoing, close monitoring of the programme, but the high uptake levels achieved in most pilot areas using school-based delivery demonstrate the feasibility of achieving high coverage levels.'
Fewer GP consultations
The national flu vaccination programme is being rolled out to all children aged 2 to 17 following advice from the UK's Joint Committee on Vaccination and Immunisation in 2012.
Pilots in seven areas of England during winter 2013/14 offered flu vaccination to children aged between 4 and 11 years, including Bury, Cumbria, Gateshead, Leicester City, East Leicestershire and Rutland, South East Essex, and the London Boroughs of Havering and Newham.
Researchers from PHE compared data on indicators that tracked the spread of flu from pilot and non-pilot areas.
GP consultation rates were 17.7 per 100,000 in pilot areas versus 64.5 per 100,000 in non-pilot areas. Similarly, the proportion of swabs testing positive for the flu virus in primary care was 8.5% versus 16.2%, and the share of emergency department attendances for flu were 5.5% versus 8.7%.
However, there was little effect on hospitalisations for flu between pilot and control areas among the wider population.
Writing in the journal Eurosurvelliance, PHE researchers said the findings highlighted the 'apparent value' of vaccination primary school children.
They said: 'The encouraging uptake levels achieved in most pilot areas demonstrate the feasibility of delivering such a programme in this population. While the estimates of programme impact were not statistically significant, it is encouraging that both direct and indirect impact (higher estimates in non-pilot relative to pilot areas) was seen across a range of surveillance schemes in primary care.'