A subset of countries and areas monitor 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 infections (SARI).
1.1) Hospitalized laboratory-confirmed influenza cases – ICUs
For week 20/2023, 2 laboratory-confirmed influenza cases were reported from ICU wards (in Sweden). One influenza type A virus and one type B virus were detected. No viruses were ascribed to a subtype or lineage.
Since week 40/2022, 2 766 influenza type A (89%) and 334 type B (11%) viruses were detected (in Czechia (n=143), France (n=957), Ireland (n=151), Sweden (n=345) and United Kingdom (England) (n=1 504)). Of 503 subtyped influenza A viruses, 54% were A(H3) and 46% were A(H1)pdm09. No influenza B viruses were ascribed to a lineage. Of 1 586 cases with known age, 754 were 15-64 years old, 628 were 65 years and older, 123 were 0-4 years old and 81 were 5-14 years old.
1.2) Hospitalized laboratory-confirmed influenza cases – other wards
For week 20/2023, 1 laboratory-confirmed influenza case was reported from other wards (in Czechia). It was an influenza type A virus and was not ascribed to a subtype .
Since week 40/2022, 3 811 influenza type A viruses and 180 influenza type B viruses were detected from Czechia (n=174) and Ireland (n=3 817). Of 399 subtyped influenza A viruses, 63% (n=251) were A(H1)pdm09 and 37% (n=148) A(H3). The 3 991 cases with known age fell in 4 age groups: 1 714 were 65 years and older, 1 376 were 15-64 years old, 500 were 0-4 years old and 401 were 5-14 years old.