# 6007
Two weeks ago the ECDC issued a risk assessment for Europe based on the recent detection of a handful of trH3N2 swine flu cases in the United States (see ECDC Risk Assessment On trH3N2 Cases In North America).
This assessment was contained in a 7-page PDF document dated November 29th, and concluded the current threat these reassorted swine viruses pose to public health in Europe was low.
They conceded, however, that `It is possible that these triple reassortant infections will appear in Europe, particularly if there is more human-to- human transmission, which could lead to imported cases.’
Since then, we’ve reports of at least one more detection of a trH3N2 human infection – this time in West Virginia (see CDC Confirms 2 More Novel Flu Infections) – along with a trH1N2 virus in Minnesota.
In neither case did these patients have recent known contact with swine, and so these reports imply that low level human-to-human transmission may have taken place.
Accordingly, the ECDC today has issued an updated risk assessment that finds:
Conclusions and recommendations
• Another case of infection with triple reassortant swine influenza SOIVtrA(H3N2)-M has been reported in humans in the US bringing the total of such cases to 11;
• While human-to-human transmission has probably taken place in the US there are no expanding clusters of infections;
• The EU National Influenza Centres are in the midst of strengthening their capacity to detect this new virus which is not thought to be present in pigs in Europe;
• The conclusions and recommendations of the ECDC Rapid Risk Assessment of 29 November remain valid.
While the number of swine-origin novel flu infections detected in humans has increased this year, the overall numbers remain extremely low.
Influenza activity remains low across the United States (and most of the northern hemisphere) and we are not seeing the kind of explosion in cases that heralded the arrival of the 2009 H1N1 pandemic virus.
These viruses are concerning because they show that a novel virus is attempting to circulate – albeit not very efficiently, as yet – among humans.
For now, the CDC and public health agencies are increasing their surveillance and testing for this virus, and are doing epidemiological investigations looking for signs of ongoing community transmission.
Whether this trH3N2 virus learns to adapt well enough to human physiology to pose a greater public health threat down the road is something we will simply have to wait to see.
