#VisualAbstract: Patterns of Influenza Vaccination and Vaccine Effectiveness Among US Children

1. The full two-dose influenza vaccination series was significantly more effective in preventing future influenza compared to partial vaccination.

Evidence Rating Level: 2 (Good)

Childhood influenza is a significant health burden, with vaccination being the primary strategy to prevent transmission. Guidelines suggest a primer dose followed by a booster for patients receiving the influenza vaccine for the first time. Few studies to-date have investigated the clinical importance of vaccination sequence and outcomes in children who receive one dose rather than the recommended full two-dose series for initial vaccination against influenza. . This case-control study of 7,533 children (46% female) from the US Influenza Vaccine Effectiveness Network sought to determine vaccine effectiveness (VE) based on this sequence. This study was performed during periods of local influenza transmission between November 4, 2014 and April 12, 2018. Children between the ages of six months and eight years presenting within seven days of onset of acute respiratory tract illness with cough were included. A total of 52% of the sample was unvaccinated, 9% were partially vaccinated, and 39% were fully vaccinated. Among fully vaccinated children, adjusted VE against influenza was 51% while VE was 41% among children partially vaccinated. The VE of a two-dose series among 1,519 vaccine-naïve children during recruitment season was 53% (95% CI 28% to 70%) while the VE of just one dose was 23% (95% CI -11% to 47%). The full two-dose series resulted in decreased likelihood of testing positive for influenza compared to partial vaccination (adjusted OR 0.57, 95% CI 0.35 to 0.93) in previously vaccine naïve children. This study highlights the importance of receiving the two-dose influenza series and ensuring that children have access to vaccination.

Click to read the study in JAMA Pediatrics

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