As noted in some of the previous articles [6, 13, 16, 17], the estimation of the SEYLL not only plays an important role in the evaluation of the extent of public health problems, but also in estimating the social and economic loss. Indeed, the commonly used SEYLL enables the severity of the specific infection and also the relative importance of the different causes of death to be determined. The results of this study indicate that after 8 years since the start of MERS-CoV pandemic, the overall %CFR associated with it is still high (31.1%). Perhaps one of the reasons for this is the lack of a vaccine or specific treatment for fighting against this infection till now and all treatments are supportive and often they are based on the patient’s clinical condition.
Our finding shows that 60.8% of MERS patients had one or more comorbidity. Most of the previously published studies of MERS-CoV declared that comorbidities could have a substantial impact on MERS prognosis and severity of disease [12, 18,19,20]. Until more is understood about MERS-CoV infection, we believe that patients with diabetes mellitus, hypertension, ischemic heart disease, and end-stage renal diseases should be considered at a higher risk for MERS-CoV infection and in the triage, these patients seem to be prioritized for treatment.
The available data indicates that in all age groups, male MERS cases had a higher SEYLL (10,702 years) in comparison to the female MERS cases (3817.5 years). Previous research has demonstrated a significant difference in mortality related to MERS between men and women [9, 21].. In line with our finding, Maniecka-Bryla et al. found that men diagnosed with the respiratory system disease in comparison to women had a higher SEYLL . We would like the SEYLL to decrease over time; however, with a bird’s-eye view to Fig. 1, this pattern is changing since mid-2018 and the burden of MERS-CoV infection in MERS patients has begun to increase in women. For the men at the same time, the downward trend of SEYLL associated with MERS-CoV infection had continued. The findings in the current study can be considered as a warning to public health authorities.
We also found that MERS patients within the age group 30–59 year-olds had the highest SEYLL (8305.5 years) in comparison to those in age groups 0–29 (SEYLL = 3744.5 years) and ≥ 60 years (SEYLL = 2466.5 years). This important issue that individuals in active age of their life had the highest SEYLL should be considered by health policy-makers in implementation of appropriate prevention and control measures to reduce the burden of premature mortality due to MERS CoV in the affected populations. Furthermore, the values of SEYLL indicate that diseases of the respiratory system play an important socio-economic role in the health status of the population worldwide.
According to the data (Fig. 1), the trend of SEYLL by year and sex in all involved countries in the world from September 23, 2012 to May 17, 2019 has decreased. It is apparent that the SEYLL values were higher in men than women for all years of the study. Overall, the highest SEYLL related to MERS-CoV infection was in the early four years of the onset of the infection (2012 to 2015) and then in mid-2015 the SEYLL in MERS cases declined rapidly and in the last four years of the MERS-CoV pandemic (216 to 2019), there has been a significant reduction in the burden of mortality related to MERS-CoV infection in morbid cases. In the literature review, we did not find any studies comparing these indices, however, this pattern was also reported during the epidemic of the severe acute respiratory syndrome (SARS) [23, 24]. The remarkable reduction in the burden of premature mortality due to MERS-CoV indicates the technical guidance on surveillance of MERS patients, also suggests standardized approach and activities for health care providers to control and prevent MERS-CoV in involved countries. Although, these measures by WHO and other related national and international organizations should continue.
The current study suffered from some limitations. Of the total cases worldwide (Since September 2012, WHO has been notified of 2449 laboratory-confirmed cases of infection with MERS-CoV.), only the details of 1789 cases were investigated in the current study. It should be noted that of 186 MERS-CoV cases in the Republic of Korea, only details related to 57 cases were published in the disease outbreak news on the WHO website. The lack of complete details for all MERS cases potentially increases the occurrence of the selection and measurement bias in the results. Another limitation of this study is choosing a life expectancy for the SEYLL measure. This index does not take into account the biological and genetic differences between men and women.
In the future, we may assess the burden of premature mortality due to the MERS-CoV infections globally to better understand the risks of this new infection for public health and also to provide a helpful recommendation for controlling and preventing it. Recommendations might change and be updated as the additional data becomes available. Indeed, despite the above limitations, such studies might be useful to implement the educational programs, to access the health care and early awareness of changes in the pattern of this relatively new infection, to reduce the higher mortality rates not only for MERS-CoV but also for the other emerging pathogens in the worldwide.