Comparison of the activities of students with different fever onsets.

<p>Students are grouped into those who never had symptoms, had fever onset by 14^th May, or fever onset 15^th May or later. The behavior of students with onset by 14^th May is similar to that of students who never became symptomatic.</p

Upper school activity frequency.

<p>A comparison of the frequency distribution of different activities among healthy upper school students.</p

Work missed by caretaker.

<p>The fraction of students reporting no ILI whose caretaker stayed home from work for the given number of days. About 9% of healthy upper school students reported a caretaker staying home from work at least one day, while about 30% of healthy lower school parents report a caretaker staying home at least one day.</p

Upper school activity levels by grade.

<p>A comparison of the activities of healthy upper school students during the school closure. Activity level in grades 11 and 12 was higher than in grades 9 and 10. Averages are given numerically.</p

Lower school activity levels by grade.

<p>Levels of activity in healthy students are lower than reported by upper school students.</p

Absenteeism by grade in upper and lower school before and after the school closure.

<p>Note different vertical axes. The lower school had significantly higher absenteeism. The mean and standard deviation about that mean for the same period of the previous year is shown in solid and dotted lines respectively.</p

Serum 25–Hydroxyvitamin D₃ and Mammography Density among Mexican Women

<div><p>Low circulating levels of vitamin D and high mammographic density (MD) have been associated with higher risk of breast cancer. Although some evidence suggested an inverse association between circulating vitamin D and MD, no studies have investigated this association among Mexican women. We examined whether serum 25−hydroxyvitamin D3 [25(OH)D3] levels were associated with MD in a cross-sectional study nested within the large Mexican Teacher's Cohort. This study included 491 premenopausal women with a mean age of 42.9 years. Serum 25(OH)D3 levels were measured by liquid chromatography/tandem mass spectrometry. Linear regression and non-linear adjusted models were used to estimate the association of MD with serum 25(OH)D3. Median serum 25(OH)D3 level was 27.3 (23.3–32.8) (ng/ml). Forty one (8%) women had 25(OH)D3 levels in the deficient range (< 20 ng/ml). Body mass index (BMI) and total physical activity were significantly correlated with 25(OH)D3 (r = −0.109, P = 0.019 and r = 0.095, P = 0.003, respectively). In the multivariable linear regression, no significant association was observed between 25(OH)D3 levels and MD overall. However, in stratified analyses, higher serum 25(OH)D3 levels (≥27.3 ng/ml) were significantly inversely associated with percent MD among women with BMI below the median (β = −0.52, P = 0.047). Although no significant association was observed between serum 25(OH)D3 and percent MD in the overall population, specific subgroups of women may benefit from higher serum 25(OH)D3 levels.</p></div

Correlation between serum 25(OH)D3 and other risk factors.

<p>Correlation between serum 25(OH)D3 and other risk factors.</p

Characteristics of the study population across predefined cut-points of serum 25(OH)D3.

<p>Characteristics of the study population across predefined cut-points of serum 25(OH)D3.</p

Fractional polynomial modelling of the association of serum 25(OH)D3 (ng/ml) with percent mammography density (MD).

<p>A model with 95%CI among women with: A) BMI < median (< 27.4 kgm²), B) BMI ≥ median (≥ 27.4 kgm²).</p