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Sunlight exposure might account for the relatively low COVID-19 morbidity and mortality in tropical countries

Muhammad et al., Tropical Biomedicine, doi:10.47665/tb.41.1.010
Mar 2024  
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Sunlight for COVID-19
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*, now with p = 0.000052 from 5 studies.
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4,400+ studies for 81 treatments.
Retrospective analysis of tropical and non-tropical countries showing significantly lower COVID-19 cases and mortality in tropical countries. The study found that specific photovoltaic power output, global horizontal irradiation, diffuse horizontal irradiation, and global tilted irradiation were inversely correlated with COVID-19 cases and mortality, suggesting that stronger sunlight exposure may lead to lower COVID-19 cases and deaths.
Muhammad et al., 25 Mar 2024, retrospective, peer-reviewed, 7 authors.
This PaperSunlightAll
Sunlight exposure might account for the relatively low COVID-19 morbidity and mortality in tropical countries
M Muhammad, S K Loong, C S Khor, A Kafle, B Bello, S Abubakar
Tropical Biomedicine, doi:10.47665/tb.41.1.010
The present study aimed at exploring whether sunlight exposure might account for the relative difference in COVID-19-related morbidity and mortality between tropical and non-tropical countries. A retrospective observational study was designed and data from the World Health Organization weekly COVID-19 epidemiological update was compiled. We examined the total number of confirmed COVID-19 cases per 100 000 population, as well as the total number of COVID-19-related mortalities per 100 000 population. Solar variables data were obtained from the Global Solar Atlas website ( These data were analyzed to determine the association of sunlight exposure to COVID-19-related morbidity and mortality in tropical and non-tropical countries. Results revealed a statistically significant decrease in the number of confirmed COVID-19 cases per 100 000 population (P<0.001), as well as the number of COVID-19-related mortalities per 100 000 population (P<0.001) between tropical and non-tropical countries. Analyses of sunlight exposure data found that specific photovoltaic power output, global horizontal irradiation, diffuse horizontal irradiation and global tilted irradiation at optimum angle were significantly inversely correlated to COVID-19-related morbidity and mortality. This suggests that stronger sunlight exposure potentially leads to lower COVID-19-related morbidity and mortality. Findings from this study suggest that the relatively low COVID-19-related morbidity and mortality in tropical countries were possibly due to better sunlight exposure that translates into adequate vitamin D status.
Conflict of interest statement The authors declare that there are no conflicts of interest.
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