Printed in Great Britain PII: SO264-410X(98)00141-8 0264-410X/98 $19+0.00 Efficacy of zanamivir for

Despite vaccination, influenza remains a common cause of morbidity in nursing homes. Chemoprophylaxis of residents with currently available antivirals is not always eflective and new agents efjfective against both influenza A and B are needed. In a randomized, unblinded pilot study, we compared 14 day chemoprophylaxis with zanamivir an antiviral which inhibits influenza neuraminidase, to standard of care during sequential influenza A and influenza B outbreaks in a 735 bed nursing home. Influenza A outbreaks were declared on 6114 epidemic units. Sixty-jive volunteers on four epidemic units were randomized to zanamivir and on two epidemic units, 23 volunteers were randomized to rimantadine. During the 14 days of prophylaxis, only four new febrile respiratoy illnesses were detected. One volunteer receiving rimantadine prophylaxis developed laboratoy-confinned influenza. Influenza B outbreaks were declared on 3114 epidemic units. Thirty-jive volunteers on two epidemic units were randomized to zanamivir and 18 volunteers on one epidemic unit were randomized to no drug. During the 14 days of prophylaxis, only one new febrile respiratoy illness was detected. One volunteer randomized to receive no drug developed laboratory-conjirmed influenza. Zanamivir appears comparably efsective to standard of care in preventing influenza-like illness and laboratoy-confirmed influenza in nursing homes, but require