Weekly influenza surveillance overview, 16-22 January 2012 - Week 3

• For week 3/2012, low influenza activity was notified by 23 of the 27 countries reporting while Bulgaria, Iceland, Italy and Spain reported medium activity. Eight countries reported local or regional spread and nine countries reported increasing clinical activity trends relative to the previous week.• Of 1092 sentinel specimens collected and tested during week 3/2012, 320 (29.3%) were positive for influenza virus. This percentage is higher than in week 2/2012 and continues an upward progression since December, the high percentage in week 52/2011 being an artefact of the Christmas/New Year holiday.• Of 1468 influenza A viruses subtyped from sentinel and non-sentinel sources since week 40/2011, 1389 (94.6%) were of the H3 subtype. Since week 40/2011, no resistance to neuraminidase inhibitors has been reported.• Since week 40/2011, 237 severe acute respiratory infection (SARI) cases have been reported by six countries. One hundred and three were laboratory-confirmed influenza cases and of those viruses typed or subtyped, 15 were A(H1N1)pdm09, 48 were A(H3) and six were type B influenza viruses.• Influenza activity is slowly increasing in countries scattered accoss Europe and is currently dominated by A(H3N2) viruses though with A(H1N1) also being important in some of the severe cases.