Shortcomings of Vitamin D-Based Model Simulations of Seasonal Influenza

Shaman, Jeffrey; Jeon, Christie Y.; Giovannucci, Edward; Lipsitch, Marc

doi:10.1371/journal.pone.0020743

Cited by 43 publications

(24 citation statements)

References 23 publications

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“…While we know that the UV radiation in sunlight is associated with influenza virus inactivation (Sagripanti and Lytle, 2007), it has been postulated that vitamin D, stimulated by UV radiation, also modulates the immune system that protects against influenza virus. However, this postulation remains inconclusive since Shaman et al (2011) have shown using human serum level data that vitamin D is unlikely to having contributed to influenza seasonality.…”

Section: Introductionmentioning

confidence: 99%

Associations between seasonal influenza and meteorological parameters in Costa Rica, Honduras and Nicaragua

Soebiyanto

Clará²,

Jara

et al. 2015

Geospat Health

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Seasonal influenza affects a considerable proportion of the global population each year. We assessed the association between subnational influenza activity and temperature, specific humidity and rainfall in three Central America countries, i.e. Costa Rica, Honduras and Nicaragua. Using virologic data from each country's national influenza centre, rainfall from the Tropical Rainfall Measuring Mission and air temperature and specific humidity data from the Global Land Data Assimilation System, we applied logistic regression methods for each of the five sub-national locations studied. Influenza activity was represented by the weekly proportion of respiratory specimens that tested positive for influenza. The models were adjusted for the potentially confounding co-circulating respiratory viruses, seasonality and previous weeks' influenza activity. We found that influenza activity was proportionally associated (P<0.05) with specific humidity in all locations [odds ratio (OR) 1.21-1.56 per g/kg], while associations with temperature (OR 0.69-0.81 per °C) and rainfall (OR 1.01-1.06 per mm/day) were location-dependent. Among the meteorological parameters, specific humidity had the highest contribution (~3-15%) to the model in all but one location. As model validation, we estimated influenza activity for periods, in which the data was not used in training the models. The correlation coefficients between the estimates and the observed were ≤0.1 in 2 locations and between 0.6-0.86 in three others. In conclusion, our study revealed a proportional association between influenza activity and specific humidity in selected areas from the three Central America countries.

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Section: Introductionmentioning

confidence: 99%

Associations between seasonal influenza and meteorological parameters in Costa Rica, Honduras and Nicaragua

Soebiyanto

Clará²,

Jara

et al. 2015

Geospat Health

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“…Despite the potentially enormous influence of vitamin D on health, there is a paucity of population-based data on the seasonality of serum vitamin D levels [20]. This paper provides estimates of the temperate boreal seasonality of serum 25-hydroxyvitamin D (hereinafter 25OHD), which may be extrapolated to other studies.…”

Section: Introductionmentioning

confidence: 99%

Vitamin D (25OHD) Serum Seasonality in the United States

2013

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BackgroundVitamin D is an important micronutrient for health. Hypovitaminosis D is thought to play a role in the seasonality of a number of diseases and adverse health conditions. To refine hypotheses about the links between vitamin D and seasonal diseases, good estimates of the cyclicality of serum vitamin D are necessary.ObjectivesThe objective of this study is to describe quantitatively the cyclicality of 25-hydroxyvitamin D (25OHD) in the United States. We provide a statistical analysis with weekly time resolution, in comparison to the quarterly (winter/spring/summer/fall) estimates already in the literature.MethodsWe analyzed time series data on 25OHD, spanning 287 consecutive weeks. The pooled data set comes from 3.44 million serum samples from the United States. We statistically analyzed the proportion of sera that were vitamin D sufficient, defined as 25OHD ng/mL, as a function of date.ResultsIn the United States, serum 25OHD follows a lagged pattern relative to the astronomical seasons, peaking in late summer (August) and troughing in late winter (February). Airmass, which is a function of solar altitude, fits the 25OHD data very well when lagged by 8 weeks.ConclusionsSerum vitamin D levels can be modeled as a function of date, working through a double-log transformation of minimal solar airmass (easily calculated from solar altitude, retrievable from an online solar altitude/azimuth table).

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“…The outbreak and spread of influenza is a complex process, clearly influenced by the virulence of the influenza virus, the immunity of the host, and frequency of contacts between hosts. Research conducted in the last few decades has described a number of factors that influence the transmission and spread of influenza, including (1) mutation of the viruses and the fluctuating of population immunity levels, such as the emergence of new virus subtypes [10,11], changes in immunity levels caused by changes in melatonin [12] and vitamin D levels [13][14][15]; (2) variations in host behavior and the frequency of population contact and travel [16], such as the movements associated with school terms and holidays [17,18]; and (3) the survival and transmission abilities of viruses affected by variations in temperature and absolute humidity, and movements of the upper atmosphere [19].…”

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confidence: 99%