A study of the impact of massive population crowding on the incidence of COVID-19 in Iraq during the fortieth ceremony in 2020
Mustafa Nema A Ali, Sahar A. Majeed, Suhad T. Zamil, Suaad T. Zamil, Ekhlas Sabah Hassan, Fadhaa Abdulameer Ghafil, Rana Talib, Fatima Ha, Haider W. Mardan, Hussein Abdulkadhim A
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ABSTRACT
Background: One of the most important factors in the transmission of COVID-19 is the people crowding. This factor may enhance both increases in viral transmission and the emergence of herd immunity. However, as a rule, population crowding in religious ceremonies should logically cause a peak rise in COVID-19 incidence before the commencement of the immunity against the virus. The striking observation in this 40th ceremony in Iraq during 2020 is the occurrence of the reverse to the expected rise in the number of COVID-19 infections and deaths during the massive visitants crowding.
Aim: To assess, analyze and interpret the primary observation of the decrease in the incidence of COVID-19 during the 40th ceremony in Iraq 2020 despite approximately 14 million visitants had agglomerated during this visit.
Methods: This study was designed to assess the linear regression model of the incidence of COVID-19 during the days of Safar for the middle and southern Iraqi governorates in which almost all contributed to the ceremony in comparison with the control northern governorates population. The official registry of CMC for COVID-19 and the official northern and southern electronic counter of the visitants to Karbala were used whereas the direct visitant's contact and exposure were estimated by direct sample reviewing. Suspected cases are exclusively diagnosed based on PCR tests that belong to the formal accredited national lab with or without a chest CT scan.
Results: showed a significant decline in COVID-19 incidence and mortality soon after the commencement of the ceremony for the test population that participated in the visit to Karbala. The slope was -23 (protective) as a reverse to the expected sharp rise in the incidence due to the massive visitants’ exposure. This result was compared to the control northern Iraqi population which revealed an increased rate of COVID-19 incidence and death indicated as a positive slope (11.5) during the same comparative period.
The study had reviewed several possible medical causes of this unexpected decrease in COVID-19 incidence during this ceremony, however, no one can satisfactorily interpret the findings.
Conclusion: From the overall results, further reviewing of the nature of community attitude and its role in the severity and incidence of the epidemics is mandatory for the health system decisions.
Keywords: COVID-19, RNA virus, 40th ceremony, Arba’een pilgrimage