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7 percent less likely to get immune mediated disease if born in the fall – July 2012

Month of birth, vitamin D and risk of immune mediated disease: a case control study

BMC Medicine 2012, 10:69 doi:10.1186/1741-7015-10-69
Giulio Disanto, George Chaplin, Julia M Morahan, Gavin Giovannoni, Elina Hypponen, George C Ebers and Sreeram V Ramagopalan

A season of birth effect in immune-mediated diseases (ID) such as multiple sclerosis and type 1 diabetes has been consistently reported. We aimed to investigate whether season of birth influences the risk of rheumatoid arthritis, Crohn's disease, ulcerative colitis and systemic lupus erythematosus in addition to multiple sclerosis, and to explore the correlation between the risk of ID and predicted ultraviolet B (UVB) light exposure and vitamin D status during gestation.

The monthly distribution of births of patients with ID from the UK (n = 115,172) was compared to that of the general population using the Cosinor test. Predicted UVB radiation and vitamin D status in different time windows during pregnancy were calculated for each month of birth and correlated with risk of ID using the Spearman's correlation coefficient.

The distributions of ID births significantly differed from that of the general population (P = 5e-12) with a peak in April (odds ratio = 1.045, 95% confidence interval = 1.024, 1.067, P <0.0001) and a trough in October (odds ratio = 0.945, 95% confidence interval = 0.925, 0.966, P <0.0001). Stratification by disease subtype showed seasonality in all ID but Crohn's disease. The risk of ID was inversely correlated with predicted second trimester UVB exposure (Spearman's rho = -0.49, P = 0.00005) and third trimester vitamin D status (Spearman's rho = -0.44, P = 0.0003).

The risk of different ID in the UK is significantly influenced by the season of birth, suggesting the presence of a shared seasonal risk factor or factors predisposing to ID. Gestational UVB and vitamin D exposure may be implicated in the aetiology of ID.
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October births are 12% less likely to get influenza (they think because of vaccination) - Feb 2024

Optimal timing of influenza vaccination in young children: population based cohort study
BMJ 2024; 384 doi: https://doi.org/10.1136/bmj-2023-077076 (Published 21 February 2024)
Christopher M Worsham, assistant professor1 2 3, Charles F Bray, research assistant1, Anupam B Jena, Joseph P Newhouse professor of health care policy and medicine1 2 4

Objective To assess optimal timing of influenza vaccination in young children.

Design Population based cohort study.

Setting United States.

Participants Commercially insured children aged 2-5 years who were vaccinated against influenza during 2011-18.

Main outcome measure Rates of diagnosis of influenza among children who were vaccinated against influenza, by birth month.

Results Overall, 819 223 children aged 2-5 received influenza vaccination. Children vaccinated in November and December were least likely to have a diagnosis of influenza, a finding that may be confounded by unmeasured factors that influence the timing of vaccination and risk of influenza. Vaccination commonly occurred on days of preventive care visits and during birth months. Children born in October were disproportionately vaccinated in October and were, on average, vaccinated later than children born in August and earlier than those born in December. Children born in October had the lowest rate of influenza diagnosis (for example, 2.7% (6016/224 540) versus 3.0% (6462/212 622) for those born in August; adjusted odds ratio 0.88, 95% confidence interval 0.85 to 0.92).

Conclusions In a quasi-experimental analysis of young children vaccinated against influenza, birth month was associated with the timing of vaccination through its influence on the timing of preventive care visits. Children born in October were most likely to be vaccinated in October and least likely to have a diagnosis of influenza, consistent with recommendations promoting October vaccination.
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Attached files

ID Name Comment Uploaded Size Downloads
20899 Month of birth, vitamin D and risk of immune-mediated_CompressPdf.pdf admin 02 Mar, 2024 287.38 Kb 35
1444 Immune disease vs month of birth.pdf admin 07 Jul, 2012 1.70 Mb 1050
1443 Odds ratio vs month.jpg admin 07 Jul, 2012 22.59 Kb 1483