MERS transmission and risk factors: a systematic review

Park, Ji-Eun; Jung, Soyoung; Kim, Aeran; Park, Ji-Eun

The transmissibility and severity of MERS were different by outbreak countries, especially between the Middle East area and South Korea. The virus, host, and environmental factors may be the causes of the MERS outbreakrelated differences between the two regions. From the standpoint of viral factors, there was a mutation of the MERS coronavirus (MERS-CoV) in the South Korea outbreak. Kim et al. [60] reported a point mutation in the receptor-binding domain of the viral spike protein in MERS-CoV, and another study showed that MERS-CoV in South Korea had higher genetic variability and mutation rates [61] . Individual characteristics can also affect MERS transmission. As previous studies showed, there is an association between older age and MERS infection [43] , severity [48] , and mortality [4, 50] , and the population structure may be related to transmission and severity. Additionally, individuals aware of MERS were found to be more likely to practice preventive behaviour [62] , which differed by demographic characteristics [63, 64] . The transmission environment may also contribute to the difference. While many MERS cases were contracted through exposure to camels in Saudi Arabia [42] , the South Korea outbreak involved multiple generations of secondary infections caused by intra-hospital and hospital-tohospital transmission [3, 65] . Strategies considering various factors are therefore needed to assess the impact of MERS and to better control its spread.