Epidemiological and virological assessment of influenza activity in Europe during the 2003-2004 season

Abstract

The 2003-2004 influenza season in Europe was dominated by the spread of the new drift variant A/Fujian/411/2002 (H3N2)-like virus which was not perfectly matched with the A(H3N2) component of the influenza vaccine. Sporadic cases of this virus were detected in Europe at the end of the 2002-2003 season and influenza activity associated with this virus began relatively early during the 2003-2004 season. Generally, influenza activity first occurred in the west of Europe (Ireland, the United Kingdom and the Iberian Peninsula) in October/November and gradually moved east across Europe, affecting Latvia, Lithuania and Poland during the months of January and February 2004. In general, the intensity of clinical activity was higher than during the 2002-2003 season (in 13 out of 20 networks) and, in countries reporting age specific data, the highest consultation incidences were observed among children aged 0-14. However, despite the emergence of the A(H3N2) drift variant, clinical incidences were not especially high compared with historical data. The composition of the 2004-2005 influenza vaccine has been modified compared with the 2003-2004 season and includes an A/Fujian/411/2002 (H3N2)-like virus strain and a new B virus strain (a B/Shanghai/361/2002-like virus).

Impact of flu on hospital admissions during 4 flu seasons in Spain, 2000–2004

“…influenza confirmation), limiting our capacity to estimate the real number of hospitalisations from influenza infection. Part of the hospitalisations that we have considered to be flu-associated might in fact be due to parainfluenza virus, respiratory synctical virus (RSV) or adenovirus [10,23]. It is likely that different respiratory virus' have different effects in different age groups.…”

Amantadine Resistance among Porcine H1N1, H1N2, and H3N2 Influenza A Viruses Isolated in Germany between 1981 and 2001

“…At present, H1N1, H1N2, and H3N2 subtypes of infl uenza A viruses are circulating in Europe [4,5] . All three subtypes have also been isolated from pigs showing clinical symptoms during different outbreaks in Germany between 1981 and 2001 [6,7] .…”

“…Only aquatic birds permit replication of all known infl uenza A virus subtypes (H1-16, N1-9). H1N1, H1N2, and H3N2 subtypes are circulating in the human population of Europe [4,5] . The same subtypes were isolated from swine in Germany [6,7] .…”

Recent Human Influenza A/H3N2 Virus Evolution Driven by Novel Selection Factors in Addition to Antigenic Drift

“…One important evolutionary event involved the emergence of the A/Fujian/411/2002-like (Fujian-like) viruses associated with the moderately severe epidemic of the 2003–2004 influenza season [16–18]. With diminished protection afforded by the influenza vaccine strains, pneumonia and influenza deaths in the United States during the 2003–2004 season exceeded the epidemic threshold for 9 consecutive weeks [19].…”