Asymptomatic Severe Acute Respiratory Syndrome–associated Coronavirus Infection

Asymptomatic Severe Acute Respiratory Syndrome-associated Coronavirus InfectionTo the Editor: An outbreak of severe acute respiratory syndrome (SARS) began in Hong Kong in March 2003.As of May 29, 2003, a total of 1,732 cases were confirmed; 381 case-patients were healthcare workers and medical students.Clinical features, treatment protocols, and outcomes have been previously reported by various local experts (1-3).The etiologic agent is a SARSassociated coronavirus (SARS-CoV) (1).However, no asymptomatic case of SARS-CoV infection has been previously reported (4).In addition, in Hong Kong, blood donors have not shown any detectable antibody to SARS-CoV (1).We report a case of possible asymptomatic SARS-CoV infection in Hong Kong.The case-patient is a registered nurse working in Princess Margaret Hospital, the major infectious diseases hospital that treated >600 SARS patients in Hong Kong.Within this hospital, >800 frontline staff members have participated in direct care of SARS patients, and SARS developed in 62 of these staff members.All healthcare workers working in SARS wards followed the same infection control measures, wearing a N-95 respirator, eye shield, disposable cap, water-resistant gown, and gloves.Gowns and equipment were removed before the staff left the SARS wards.We performed serologic testing of the first 101 healthcare workers (doctors, nurses, healthcare assistants) who worked in the SARS wards but in whom SARS did not develop.The serologic testing was performed 7-8 weeks after the healthcare workers were first exposed to SARS patients.