Vaccine only provides ‘limited protection’ against ‘B’ strain

THERE are two dominant strains of flu currently circulating – but the vaccine only provides limited protection against them.

The A H3N2 strain, which has been dubbed ‘Aussie flu’ despite being the same flu Ireland had last year, is predominantly affecting people aged over 65, while the B strain is mainly being seen in people aged under 20.

Dr Kevin Kelleher, director of the

Health Protection Surveillance Centre, said the current flu vaccine “protects against the A strain, but not totally against the B strain so far as we can see at this stage”.

The vaccine is said to be 40pc-60pc effective, although its precise efficacy will only be known at the end of the flu season when all the data is analysed.

“Clinically at the start of our season this year it was 50/50 between the two strains. That’s unusual and has never happened before.

“It shows that the most predictable thing about flu is its unpredictability,” he said. “The A strain is the same one as we had last year and the same one they got in Australia during the summer. It has been called Aussie flu but really it’s the Irish flu that the Australians had.” Dr Cillian De Gascun, director of the UCD National Virus Reference Laboratory, said: “From our own laboratory data, we believe influenza B might be taking the lead and becoming the dominant strain.”

He said rather than being a new phenomenon, influenza A H3N2 has been one of our seasonal strains of flu since 1962. He said that while the virus was “continually evolving”, there was “nothing to suggest it’s been more severe than in previous years”. Referring to the vaccine, he said: “We partake in a Europewide vaccine efficacy study. We can only get the full picture at the end of the season.

“But based on Irish data from last year, the vaccine worked reasonably well and there is no reason to believe it won’t this year.

“An efficacy rate of 50pc-60pc is pretty good. It’s still the most effective measure we have.”