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Middle East respiratory syndrome coronavirus (MERS-CoV) was first isolated in 2012. The largest known outbreak outside the Middle East occurred in South Korea in 2015. As of 29 June 2016, 1769 laboratory-confirmed cases (630 deaths; 35.6 % case fatality rate [CFR]) had been reported from 26 countries, particularly in the Middle East. However, the CFR for hospital outbreaks was higher than that of family clusters in the Middle East and Korea. Here, we compared the mortality rates for 51 nosocomial outbreaks in the Middle East and one outbreak of MERS-CoV in South Korea. Our findings showed the CFR in the Middle East was much higher than that in South Korea (25.9 % [56/216] vs. 13.8 % [24/174], p = 0.003). Infected individuals who died were, on average, older than those who survived in both the Middle East (64 years [25-98] vs. 46 years [2-85], p = 0.000) and South Korea (68 years [49-82] vs. 53.5 years [16-87], p = 0.000). Similarly, the co-morbidity rates for the fatal cases were statistically higher than for the nonfatal cases in both the Middle East (64.3 % [36/56] vs. 28.1 % [45/160], p = 0.000) and South Korea (45.8 % [11/24] vs. 12.0 % [18/150], p = 0.000). The median number of days from onset to confirmation of infection in the fatal cases was longer than that for survivors from the Middle East (8 days [1-47] vs. 4 days [0-14], p = 0.009). Thus, older age, pre-existing concurrent diseases, and delayed confirmation increase the odds of a fatal outcome in nosocomial MERS-CoV outbreaks in the Middle East and South Korea. [ABSTRACT FROM AUTHOR]

A novel avian influenza A (H7N9) virus caused 5-10 % mild and 30.5 % fatal human infections as of December 10, 2015. In order to investigate the reason for the higher rate of fatal outcome of this infection, this study compared the molecular epidemiology and virology of avian influenza A (H7N9) viruses from mild (N = 14), severe (N = 50) and fatal (N = 35) cases, as well as from non-human hosts (N = 73). The epidemiological results showed that the average age of the people in the mild, severe and fatal groups was 27.6, 52 and 62 years old, respectively ( p < 0.001). Males accounted for 42.9 % (6/14), 58.0 % (29/50), and 74.3 % (26/35) of cases in the mild, severe and fatal group respectively ( p = 0.094). Median days from onset to start of antiviral treatment were 2, 5 and 7 days in the mild, severe and fatal group, respectively ( p = 0.002). The median time from onset to discharge/death was 12, 40 and 19 days in the mild, severe and fatal group, respectively ( p < 0.001). Analysis of whole genome sequences showed that PB2 (E627K), NA (R294K) and PA (V100A) mutations were markedly associated with an increased fatality rate, while HA (N276D) and PB2 (N559T) mutations were clearly related to mild cases. There were no differences in the genotypes, adaptation to mammalian hosts, and genetic identity between the three types of infection. In conclusion, advanced age and delayed confirmation of diagnosis and antiviral intervention were risk factors for death. Furthermore, PB2 (E627K), NA (R294K) and PA (V100A) mutations might contribute to a fatal outcome in human H7N9 infection. [ABSTRACT FROM AUTHOR]