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Although no cases of human H3N2v infection have been reported outside of the United States, other nations are understandably watching the situation closely, and are preparing for the possibility of seeing this flu virus imported into their region.
Last week Hong Kong made H3N2v a reportable disease (see Hong Kong Takes Notice Of H3N2v), while the ECDC published a risk assessment on the virus last Friday (see H3N2v: CDC Update & ECDC Risk Assessment).
Although the threat from this virus is considered low at this time, today the HPA published recommendations that travelers returning from the United States with `an influenza-like illness who have had contact with pigs in the USA within five days of the onset of their illness, should be investigated further’.
Update on new swine flu in the US
21 August 2012
The Health Protection Agency (HPA) is aware there have been nearly 250 human cases of swine-origin influenza A(H3N2)v virus in the recent USA outbreak since it was first identified in August 2011.
The virus has mainly affected children and young adults and is mild in nature. Most cases have documented contact with pigs, although in one small cluster of six cases reported in December 2011, there may have been limited human to human transmission. This virus has not been identified in pigs or humans in the UK.
The HPA has recommended that returning travellers with an influenza-like illness who have had contact with pigs in the USA within five days of the onset of their illness, should be investigated further. The HPA is contacting GPs to ensure they are aware of this recommendation in light of this outbreak and we are updating the website with information on this new strain.
The US Centre for Disease Control and Prevention (CDC) has advised this summer that in the US, those at increased risk of the complications of influenza, including older people, small children and those with chronic diseases, should consider avoiding pigs and swine barns.
The strain of H3N2 in the current seasonal flu vaccine is different to the A(H3N2)v although, since the virus is related to the human H3N2 influenza virus that was circulating in the 1990s, studies suggest that adults may have some immunity to this virus whereas children will not.
Professor Nick Phin, from the HPA’s influenza department said:
“There are no UK cases of this strain of H3N2 in humans or pigs and it has not spread to other countries in Europe, so the threat to the UK public is very low. We are keeping a very close watch on the situation in the US and are in contact with our American colleagues to regularly assess the risk.
“We are reassured that there is little evidence to support human to human spread and that virtually all of the cases can be associated with direct contact with pigs.
“We are now approaching this year’s flu season and so I want to take this opportunity to remind anybody who is in an ‘at risk’ group to ensure they get their flu vaccination as soon as the vaccination programme begins to ensure the best protection over the coming winter.”
