OBJECTIVES: Seasonal variations in ultraviolet B (UVB) radiation cause seasonal variations in vitamin D status. This may influence immune responses and play a role in the seasonality of influenza. METHODS: Pandemic and non-pandemic influenzas in Sweden, Norway, the USA, Singapore, and Japan were studied. Weekly/monthly influenza incidence and death rates were evaluated in view of monthly UVB fluences. RESULTS: Non-pandemic influenzas mostly occur in the winter season in temperate regions. UVB calculations show that at high latitudes very little, if any, vitamin D is produced in the skin during the winter. Even at 26°N (Okinawa) there is about four times more UVB during the summer than during the winter. In tropical regions there are two minor peaks in vitamin D photosynthesis, and practically no seasonality of influenza. Pandemics may start with a wave in an arbitrary season, while secondary waves often occur the following winter. Thus, it appears that a low vitamin D status may play a significant role in most influenzas. CONCLUSIONS: In temperate latitudes even pandemic influenzas often show a clear seasonality. The data support the hypothesis that high fluences of UVB radiation (vitamin D level), as occur in the summer, act in a protective manner with respect to influenza.
OBJECTIVES: Seasonal variations in ultraviolet B (UVB) radiation cause seasonal variations in vitamin D status. This may influence immune responses and play a role in the seasonality of influenza. METHODS: Pandemic and non-pandemic influenzas in Sweden, Norway, the USA, Singapore, and Japan were studied. Weekly/monthly influenza incidence and death rates were evaluated in view of monthly UVB fluences. RESULTS: Non-pandemic influenzas mostly occur in the winter season in temperate regions. UVB calculations show that at high latitudes very little, if any, vitamin D is produced in the skin during the winter. Even at 26°N (Okinawa) there is about four times more UVB during the summer than during the winter. In tropical regions there are two minor peaks in vitamin D photosynthesis, and practically no seasonality of influenza. Pandemics may start with a wave in an arbitrary season, while secondary waves often occur the following winter. Thus, it appears that a low vitamin D status may play a significant role in most influenzas. CONCLUSIONS: In temperate latitudes even pandemic influenzas often show a clear seasonality. The data support the hypothesis that high fluences of UVB radiation (vitamin D level), as occur in the summer, act in a protective manner with respect to influenza.
Authors: Shih-Wen Lin; David C Wheeler; Yikyung Park; Michael Spriggs; Albert R Hollenbeck; D Michal Freedman; Christian C Abnet Journal: Am J Epidemiol Date: 2013-07-17 Impact factor: 4.897
Authors: Rolf Jorde; Miles Witham; Wim Janssens; Lars Rolighed; Kyra Borchhardt; Ian H de Boer; Guri Grimnes; Moira S Hutchinson Journal: Scand J Infect Dis Date: 2011-10-25
Authors: Elizabeth P Schlaudecker; Joan P Heck; Elizabeth T Macintyre; Ruben Martinez; Caitlin N Dodd; Monica M McNeal; Mary A Staat; Jeffery E Heck; Mark C Steinhoff Journal: Pediatr Infect Dis J Date: 2012-11 Impact factor: 2.129
Authors: Ahmed S Safwat; Ahmad Hasanain; Ahmed Shahat; Mostafa AbdelRazek; Hazem Orabi; Samir K Abdul Hamid; Amany Nafee; Sally Bakkar; Mohamed Sayed Journal: World J Urol Date: 2018-10-25 Impact factor: 4.226