Via The Lancet, a timely article: Infection control and MERS-CoV in health-care workers. Excerpt:
The large number of MERS-CoV cases (229 cases) reported between April 11, 2014, and May 4, 2014, by Saudi Arabia were probably seasonal (related to the camel birthing season), reminiscent of the clusters of hospital cases that were previously confirmed in a hospital in Jordan in April, 2012,4 which involved haemodialysis units within hospitals in Al Hasa in April and May, 2013.
Sequencing of the MERS-CoV isolates from the Jeddah outbreak has shown no substantial genetic changes. The WHO Emergency Committee concluded that the increase in cases reported among health-care workers from hospitals in Jeddah was amplified due to overcrowding and inadequate infection control measures.
Acute viral respiratory tract infections, such as severe acute respiratory syndrome (SARS) and MERS, are predominantly spread by large respiratory droplets (≥10 μm in diameter) during coughing and sneezing, whereas contact with fomite (including hand contamination with subsequent self-inoculation) might be another potential route of transmission.
The SARS outbreak in 2003 provided good lessons for the evaluation of environmental influences on the aerosol transmission of communicable respiratory diseases and the importance of good infection control measures in the prevention of nosocomial infections.
One intriguing aspect of the 2003 SARS epidemic was the occurrence of super-spreading events, which accounted for 71·1% and 74·8% of SARS cases in Hong Kong and Singapore, respectively. During the SARS outbreak in 2003, SARS-coronavirus (CoV) was moderately transmissible, with 2·7 secondary infections for every index case. However, infectivity was substantially increased when coupled with environmental factors: 138 patients, many of whom were health-care workers, were infected within 2 weeks as a result of exposure to one patient with community-acquired pneumonia who was admitted to a general medical ward.
This super-spreading event seemed to be related to overcrowding and poor ventilation in the dry air-conditioned hospital ward, together with some contribution by the use of a jet nebuliser for the index case. Evidence of airborne transmission of SARS-CoV was also supported by positive air samples of the virus obtained from a hospital room occupied by a patient with SARS in Toronto, Canada.
On the basis of analysis of data in a case-control study that involved 124 medical wards in 26 hospitals in Guangzhou, China, and Hong Kong, the risk factors for super-spreading events of SARS-CoV in the hospital setting were: close separation between beds of less than 1 m; performance of resuscitation; staff working while experiencing symptoms; and patients requiring oxygen or non-invasive ventilation therapy. This study also showed that the availability of washing or changing facilities for health-care staff was a protective factor.
These findings have important clinical implications in the prevention of nosocomial infections of MERS-CoV in health-care facilities in the Middle East.