Prevention of nosocomial transmission of swine-origin pandemic influenza virus A/H1N1 by infection control bundle

Abstract

After the outbreak of severe acute respiratory syndrome in Hong Kong, the importance of preventing nosocomial transmission of respiratory viruses has become a top priority in infection control. During the containment and early mitigation phases of the swine-origin influenza virus (S-OIV) A H1N1 pandemic, an infection control bundle consisting of multiple coherent measures was organised by our infection control team to minimise nosocomial transmission. This included repeated open staff forum achieving high attendance; early recognition of index cases among inpatients by liberal testing; early relief of sick staff from work; directly observed hand hygiene practice during outbreaks; and monitoring of compliance with infection control practice. During the first 100 days (from 1 May to 8 August 2009) when the first 100 laboratory-confirmed patients with S-OIV and 12 infected healthcare workers (HCWs) were identified, a total of 836 asymptomatic exposed persons (184 patients and 652 HCWs) were required to undergo a seven-day medical surveillance. The infection control nurses monitored them for the onset of symptoms. Four (0.48%) exposed persons (one house officer, two non-clinical staff, and one patient) were virologically confirmed with S-OIV. Not wearing a surgical mask either by the exposed persons during contact with the index cases (4/4 vs 264/832, P=0.010) or vice versa (4/4 vs 300/832, P=0.017, Fisher's exact test) were found to be significant risk factors for nosocomial acquisition of S-OIV.

Figure 1

(A) Contact tracing for hospitalised patients diagnosed to have swine-origin influenza virus (S-OIV) A H1N1. ^a Single room isolation until reverse transcription–polymerase chain reaction (RT-PCR) result available in phase 1 and cohort nursing of confirmed cases in phase 2. ^b Median length of stay: 4 days (range: 1–32). ^c Median length of stay: 2 days (range: 1–8), before confirmation of S-OIV. ^d Twenty-one doctors, 77 nurses, 37 ward assistants. ^e Sixty-one doctors, 133 nurses, 67 ward assistants, nine physiotherapists, two occupational therapists, three radiographers, one pharmacist. ^f Oseltamivir post-exposure prophylaxis was given to 32 patients with unprotected exposure. (B) Contact tracing for healthcare workers diagnosed to have S-OIV A H1N1. ^a Four doctors, four nurses, one ward assistant, one dispenser, one technician, and one clerk. ^b Forty-nine doctors, 99 nurses, 38 ward assistants. ^c Two nurses, 17 ward assistants, three technicians, and 33 pharmacists/dispensers.