RESEARCH - The seasonality of pandemic and non-pandemic influenzas: the roles of solar radiation and vitamin D

[Guest guest]

Int J Infect Dis. 2010 Dec;14(12):e1099-105. Epub 2010 Oct 29.

The seasonality of pandemic and non-pandemic influenzas: the roles of

solar radiation and vitamin D.

Juzeniene A, Ma LW, Kwitniewski M, Polev GA, Lagunova Z, Dahlback A, Moan J.

Department of Radiation Biology, Institute for Cancer Research, the

Norwegian Radium Hospital, Oslo University Hospital, Montebello,

N-0310 Oslo, Norway.

Abstract

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.

PMID: 21036090

http://www.ncbi.nlm.nih.gov/pubmed/21036090

Not an MD