Severity

A subset of Member States and areas monitors severe disease related to influenza virus infection by surveillance of 1) hospitalized laboratory-confirmed influenza cases in ICUs or other wards, or 2) severe acute respiratory infection (SARI; 17 Member States or areas).

1.1) Hospitalized laboratory-confirmed influenza cases – ICUs

Among laboratory-confirmed influenza cases reported in ICUs for week 48/2019 (n=87), influenza type A viruses (n=83, 95%) were detected more frequently than influenza type B viruses (n=4, 5%).

Since week 40/2019, more influenza type A (n=218, 94%) than type B (n=15, 6%) viruses have been detected. Of 57 subtyped influenza A viruses, 32% were A(H1N1)pdm09 and 68% were A(H3N2). None of the influenza B viruses have been ascribed to a lineage. Of 21 cases with known age, 48% were 15–64 years old and 43% were 65 years and older.

1.2) Hospitalized laboratory-confirmed influenza cases – other wards

Among laboratory-confirmed influenza cases reported in wards other than ICUs for week 48/2019 (n=38), influenza type A viruses (n=28) were detected more frequently than influenza type B viruses (n=7).

Since week 40/2019, more influenza type A (n=180, 92%) than type B (n=16, 8%) viruses have been detected. Of 104 subtyped influenza A viruses, 7% were A(H1N1)pdm09 and 93% were A(H3N2). No influenza B viruses have been ascribed to a lineage. Of 196 cases with known age, 34% were 15–64 years old and 30% were 65 years and older.

2. SARI surveillance

For week 48/2019, 994 SARI cases were reported by 12 Member States or areas. In total, 176 specimens were tested for influenza viruses and 13 (7%) were positive for influenza: 1 A(H1N1)pdm09, 2 A(H3N2) and 10 type B.

Of 7 350 SARI cases reported since week 40/2019, 7 286 had a recorded age and, of these, 59% were 0-4 years old and 20% were 15-64 years old. Of the SARI cases testing positive for an influenza virus since week 40/2019 (n=64), type B viruses were the most common (n=53, 83%). Of the 10 influenza type A infected cases for which subtyping was performed, 1 was A(H1N1)pdm09 and 9 were A(H3N2) viruses. Of 5 influenza type B viruses ascribed to a lineage, all were B/Victoria lineage.

Mortality monitoring

For week 48/2019, the EuroMOMO project received data from 21 countries or areas that were included in pooled analyses. Pooled estimates of all-cause mortality were within the expected range for the time of year.