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 1/2018, increasing numbers of severe cases were reported by countries operating these surveillance systems.

For week 1/2018, 522 laboratory-confirmed influenza-infected cases from intensive care units (ICU) were reported by the Czech Republic (n=2), Denmark (n=2), Finland (n=1), France (n=236), Ireland (n=5), Spain (n=29), Sweden (n=7), and the United Kingdom (n=240) and 359 cases were reported from other wards by the Czech Republic (n=3), Denmark (n=57), Ireland (n=164), Romania (n=1) and Spain (n=134).

Since week 40/2017, 10 countries have reported laboratory-confirmed hospitalized influenza cases in ICU or other wards: 1 770 cases in ICU (France (n=812), the United Kingdom (n=664), Spain (n=224), Sweden (n=34), Ireland (n=15), Denmark (n=12), the Czech Republic (n=6) and Finland (n=3)), and 1 486 in other wards (Spain (n=687), Ireland (n=513), Denmark (n=276), the Czech Republic (n=5), Romania (n=3) and Slovakia (n=2)).

Of 1 770 cases in ICU, 1 136 (64%) were infected with type A viruses (234 A(H1N1)pdm09, 137 A(H3N2), 765 A un-subtyped) and 634 (36%) with type B viruses. A higher proportion of patients with influenza type B virus infection was observed in other wards: of 1 486 patients, 558 (38%) were infected with influenza type A (46 A(H1N1)pdm09, 96 A(H3N2), 416 A un-subtyped) and 928 (62%) with influenza B viruses.

For week 1/2018, 1 089 SARI cases were reported by 10 countries from which 114 specimens were tested for influenza viruses with 10 (Albania (n=1), Armenia (n=2), Kosovo (n=1), Serbia (n=5) and Tajikistan (n=1)) being positive. Since week 40/2017, 13 768 SARI cases have been reported from 15 countries; of 3 265 specimens tested for influenza viruses, 113 were positive for influenza virus as reported by Armenia (n=57; 52 type B and 5 A(H1N1)pdm09), Ukraine (n=23; 1 A(H1N1)pdm09, 1 A un-subtyped and 21 type B), Kazakhstan (n=13; 6 A(H3N2) and 7 type B), Serbia (n=6; 1 A(H1N1)pdm09 and 5 type B), Tajikistan (n=4; 1 A un-subtyped and 3 type B), Albania (n=3; 2 A(H1N1)pdm09 and 1 type B), Belarus (n=2; 2 A(H3N2)), the Russian Federation (n=2; 2 A(H3N2), Uzbekistan (n=2; 1 A(H1N1)pdm09 and 1 type B), and Kosovo (n=1; 1 A un-subtyped).

Mortality monitoring

Data from 16 countries or regions reporting to the EuroMOMO project were received for week 1/2018 and included in the pooled analyses of all-cause excess mortality. Over the past weeks, there has been increased mortality among the elderly, notably in the southwest (Portugal and Spain) and the United Kingdom (Scotland).