Severity

Severe disease related to influenza virus infection is monitored by surveillance of hospitalized laboratory-confirmed influenza cases or severe acute respiratory infections (SARI) in some countries. For week 45/2017, relatively low numbers of severe cases were reported by most countries with these surveillance systems.

Since week 40/2017, 6 countries have reported laboratory-confirmed hospitalized influenza cases in intensive care units (ICU) or other wards: 26 cases in ICU (18 in the United Kingdom and 5 in Spain, while the Czech Republic, Denmark and Sweden each had 1) and 42 in other wards (19 in Ireland, 16 in Denmark, 5 in Spain and 2 in the Czech Republic). Of 26 cases in ICU, 20 (77%) were infected with type A viruses (4 A(H1N1)pdm09, 6 A(H3N2), 10 A unsubtyped) and 6 (23%) with type B viruses. A similar distribution was observed in other wards: of 42 patients, 31 (74%) were infected with influenza A (8 A(H1N1)pdm09, 9 A(H3N2), 14 A unsubtyped) and 11 (26%) with influenza B viruses.

For week 45/2017, 767 SARI cases were reported from 11 countries and none of 107 specimens tested for influenza viruses were positive. Kazakhstan had a relatively high number of cases (n=396) and accounted for 52% of all cases. Since week 40/2017, 4 234 SARI cases have been reported from 14 countries; of 1 021 specimens tested for influenza viruses, 6 were positive for influenza virus, 3 from Tajikistan (1 A unsubtyped and 2 type B) and 3 from Kazakhstan (1 A(H3N2) and 2 type B).

Mortality Monitoring

Data from 19 countries or regions reporting to the EuroMOMO project were received for week 45/2017 and included in the pooled analyses of excess all-cause mortality. All-cause mortality was within normal ranges in the past few weeks as expected for this time of year.