Vaccine Effectiveness Against Medically Attended, Laboratory-Confirmed Influenza Among Children Aged 6 to 59 Months, 2003-2004

Emory University, Atlanta, Georgia, United States
PEDIATRICS (Impact Factor: 5.47). 04/2007; 119(3):e587-95. DOI: 10.1542/peds.2006-1878
Source: PubMed


Influenza is a leading cause of illness among children. Studies rarely have measured influenza vaccine effectiveness among young children, particularly when antigenic match between vaccine and circulating viruses is suboptimal. We assessed vaccine effectiveness against medically attended, laboratory-confirmed influenza for children who were aged 6 to 59 months during the 2003-2004 influenza season.
In a case-control study that was conducted in a single pediatric practice, case patients who were aged 6 to 59 months and had laboratory-confirmed influenza were age matched 1:2 to eligible control subjects. Vaccination status was ascertained as of the date of the case patient's symptom onset. Conditional logistic regression was used to calculate vaccine effectiveness, adjusting for underlying medical conditions and health care usage.
We identified 290 influenza case patients who were seen for medical care from November 1, 2003, to January 31, 2004. Vaccine effectiveness among fully vaccinated children, compared with unvaccinated children, was 49%. Partially vaccinated children who were aged 6 to 23 months had no significant reduction in influenza (vaccine effectiveness: -70%), but partially vaccinated children who were aged 24 to 59 months had a significant (65%) reduction in influenza, compared with unvaccinated children.
Full vaccination provided measurable protection against laboratory-confirmed influenza among children who were aged 6 to 59 months during a season with suboptimal vaccine match. No vaccine effectiveness was identified with partial vaccination among children who were aged 6 to 23 months, affirming that children need to be fully vaccinated to obtain protective effects. These results strengthen the evidence of the vaccine's ability to reduce substantially the burden of disease in this age group.

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    • "A moderate boost on cross-reactive response to a novel influenza virus by seasonal vaccination may not lead to a complete protection against a pandemic, but might reduce the burden of infections substantially in affected subjects, which is often seen in young children receiving partial vaccination [16]–[18]. A surveillance study on military service members stationed in the US soil has found that prior seasonal vaccinations between 2004–2009 were positively associated with protection against clinically apparent and laboratory-confirmed 2009 pandemic H1N1 illness [19]. "
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    PLoS ONE 01/2011; 6(1):e16650. DOI:10.1371/journal.pone.0016650 · 3.23 Impact Factor
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    • "One result of low diagnosis is that the number of cases reported does not reflect the actual frequency of influenza. The use of rapid testing for influenza may enhance the precision of the influenza diagnosis but the reduced sensitivity of these tests means that negative test results should be confirmed with RT-PCR and/or viral culture [18,20]. "
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    BMC Infectious Diseases 06/2010; 10(1):168. DOI:10.1186/1471-2334-10-168 · 2.61 Impact Factor
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    • "However, the majority of these studies were conducted among children. In children less than 5 years of age and asthmatic children 6–17 years of age, LAIV was found to have superior efficacy and effectiveness in comparison to TIV [1] [2] [3] [4]. A limited number of studies, mostly randomized trials or experimental challenge studies, have been conducted among adults. "
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