Surveillance van het verloop van influenza-uitbraken en oseltamivir gebruik in verpleeg- en verzorgingshuizen in Nederland

Nursing home surveillance in the winter of 2003-2004 did not produce conclusive evidence as to the effect of oseltamivir on the course of influenza outbreaks after its administration to nursing home residents as post-exposition profylaxis and/or therapy. Surveillance was carried out to assess the effect of oseltamivir in protecting nursing home residents from influenza infection. The Dutch Ministry of Health had urged provision of oseltamivir to this group after a mismatch between the epidemic influenza A(H3N2) strain and the A(H3N2) vaccine strain. In our study of the effect of oseltamivir on influenza outbreaks in institutions, we found that in 6 institutions residents of all care units were administered oseltamvir profylaxis and/or therapy, while in 2 institutions all residents received only oseltamivir therapy. In one institution the method of administration varied per care-unit. Of care-units with a known treatment starting-date, no additional cases were found after the start of treatment both in 50% of the care-units that administered oseltamivir profylaxis and/or therapy (n=12) and 50% of the care-units that administered only oseltamivir therapy (n=4). One additional case of clinical influenza was found in 2 care-units administered oseltamivir profylaxis and/or therapy. Due to absence of control institutions and delayed administration of oseltamivir for profylaxis, it is unclear if the few additional cases were the result of oseltamivir treatment or of a natural decline in the influenza epidemic in nursing homes. A study comparing the course of the influenza outbreaks in nursing homes administering oseltamivir with those not adminstering oseltamivir could clarify the effect of oseltamivir.