Repeated influenza vaccination of healthy children and adults: borrow now, pay later?

A growing number of publications are recommending annual influenza vaccination of healthy children and adults. However, the long-term consequences of repeated influenza vaccination are unknown. We used a simple model of recurrent influenza infection to assess the likely impact of various repeated influenza vaccination scenarios. The model was based on a Markovian framework and was fitted on annual incidence rates of influenza infection by age. We found that natural influenza infection reduced the risk of being re-infected by 15.4% (95% confidence interval 7.1-23.0). Various scenarios of repeated influenza vaccination were then simulated and compared with a reference scenario where vaccination is given from age 65 years onwards. We show that repeated vaccination at a young age substantially increases the risk of influenza in older age, by a factor ranging between 1.2 (vaccination after 50 years) to 2.4 (vaccination from birth). These findings have important implications for influenza vaccination policies.

Prospective association between obesity and depression: evidence from the Alameda County Study.

OBJECTIVE: To examine the temporal relation between obesity and depression to determine if each constitutes a risk factor for the other. DESIGN: A two-wave, 5-y-observational study with all measures at both times. SUBJECTS: A total of 2123 subjects, 50 y of age and older, who participated in the 1994 and 1999 waves of the Alameda County Study. MEASUREMENTS: Obesity defined as body mass index (BMI)> or =30. Depression assessed using DSM-IV symptom criteria for major depressive episodes. Covariates include indicators of age, gender, education, marital status, social support, life events, physical health problems, and functional limitations. RESULTS: Obesity at baseline was associated with increased risk of depression 5 y later, even after controlling for depression at baseline and an array of covariates. The reverse was not true; depression did not increase the risk of future obesity. CONCLUSION: These results, the first ever on reciprocal effects between obesity and depression, add to a growing body of evidence concerning the adverse effects of obesity on mental health. More studies are needed on the relation between obesity and mental health and implications for prevention and treatment.