Het influenzaseizoen 2002/'03 in Nederland en de vaccinsamenstelling voor het seizoen 2003/'04

As in the 2000/2001 and 2001/2002 seasons, the influenza epidemic in the 2002/2003 season started late (week 7 of 2003) and was only moderate in size. Influenza A(H₃N₂) and B viruses were detected in equal numbers among patients of general practitioners and these two viruses were therefore equally responsible for the epidemic. However, H₃N ₂ viruses dominated isolates taken from hospitals. In haemagglutination-inhibition (HI) assays most of the H₃N₂ viruses proved highly reactive with antiserum to the vaccine-reference strain A/Moscow/10/99. This was also true for a number of isolates, including those obtained from nursing home residents, closely related to the reference strain A/Finland/170/03. However, an estimated 4% of the H₃N₂ isolates belonged to the variant A/Fujian/411/02 from China, which constituted the majority of the H₃N₂ viruses isolated in Europe in the later phase of the season. This variant reacted poorly with antiserum to A/Moscow/10/99. In HI tests all influenza A(H1N1)-virus isolates and all B-virus isolates were closelyrelated to the corresponding vaccine-reference strains. Taking this data into consideration, the World Health Organization has advised the same vaccine composition for the 2003/2004season as for the 2002/2003 season, namely: A/Moscow/10/99 (H₃N₂), A/New Caledonia/20/99 (H1N1) and B/Hong Kong/330/01. There is the possibility of a mismatch occurring between the H₃N₂-vaccine strain and the circulating H₃N₂ viruses in the coming influenza season. In March and April 2003 there was an outbreak of influenza-A (H ₇N₇) fowl plague in the Netherlands. A special monitoring survey revealed that 91 people who had handled infected poultry became infected with the H₇N₇ virus. One of these later died as a result of this. None of the avian and human H₇N₇-virus isolates examined contained human or porcine influenza-A virus genes.