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Optimal timing of influenza vaccination in young children: population based cohort study
Christopher M Worsham1,2,3, Charles F Bray1, Anupam B Jena4,2,5
1Department of Health Care Policy, Harvard Medical School, Boston, MA, USA.
Insights
Optimal influenza vaccination timing for young children is crucial. Children born in October, vaccinated in October, showed the lowest influenza diagnosis rates, supporting early vaccination.
Area of Science:
- Pediatric infectious diseases
- Vaccinology
- Public health
Background:
- Influenza vaccination is recommended for children to prevent illness.
- The optimal timing for influenza vaccination in young children remains an area of investigation.
- Vaccination schedules can be influenced by factors such as birth month and preventive care visits.
Purpose of the Study:
- To assess the optimal timing of influenza vaccination in young children.
- To investigate the association between birth month, vaccination timing, and influenza diagnosis rates.
Main Methods:
- Population-based cohort study of commercially insured children aged 2-5 years in the United States.
- Analysis of influenza vaccination dates and influenza diagnosis rates from 2011-2018.
- Quasi-experimental analysis examining the influence of birth month on vaccination timing and outcomes.
Main Results:
- Over 800,000 children received influenza vaccination.
- Children vaccinated in November and December had the lowest rates of influenza diagnosis.
- Children born in October were more likely to be vaccinated in October and had the lowest influenza diagnosis rates (2.7%).
Conclusions:
- Birth month influences influenza vaccination timing in young children, primarily through preventive care visits.
- October vaccination, particularly for children born in October, is associated with reduced influenza diagnosis.
- Findings support recommendations for October influenza vaccination.
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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