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Study finds flu vaccine effectiveness ‘moderate’

25 Feb 2016

Pic: Getty Images

Influenza vaccine effectiveness (VE) was found to be moderate for H1N1 and B virus in 2014/15, and low for H3N2, a study of eight countries including Ireland has found.

Overall VE was 54.2 per cent for H1N1 and 73.1 per cent, 59.7 per cent and 22.4 per cent among those aged 0-14, 15-59 and older than 60, respectively.

For B viruses, overall VE was 48 per cent and 62.1 per cent, 41.4 per cent and 50.4 per cent among those aged 0-14, 15-59 and more than 60, respectively.

The Influenza Monitoring Vaccine Effectiveness in Europe (I-MOVE) multicentre case-control study involved analysis of more than 3,000 cases in Ireland, Germany, Hungary, Poland, Portugal, Romania and Spain.

The overall adjusted VE for H3N2 was just 14.4 per cent. The authors said the low VE was consistent with the reported mismatch between circulating and vaccine strains. There is also a hypothesis that prior immunisation may decrease the effectiveness of the vaccine.

“The low effectiveness of the influenza vaccines against A(H3N2) observed again this season underlines the need to improve the A(H3N2) component of the vaccine especially among the target group for vaccination. This would be even more important if the observed negative effect of previous vaccination was confirmed,” the authors said.

Meanwhile, the HPSC has said that influenza activity decreased by mid-February but remained at a high level, with H1N1 the dominant circulating strain. There have been 16 confirmed deaths this season.

There had been 665 hospitalisations, 341 associated with H1N1, three with (A)H3, 96 with A (not subtyped and 225 with influenza B. An outbreak of H1N1 was also confirmed at a school in the North-East of the country.

Niamh Mullen

Click here to view the full article which appeared in Irish Medical Times