Quadrivalent vaccine reduces severity of breakthrough influenza in children

  • Danier J & al.
  • Pediatr Infect Dis J
  • 1 Aug 2019

  • International Clinical Digest
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Takeaway

  • Inactivated quadrivalent influenza vaccine (IIV4) attenuates influenza severity in breakthrough cases among young children ages 6-35 months without high-risk conditions.

Why this matters

  • Data further confirm value of offering/encouraging annual influenza vaccination to young children, including those without conditions that increase risk for severity.
  • Timely diagnosis with available diagnostic tests is essential to avert hospitalisation.

Key results

  • 12,018 children; median age, 22 months.
  • 6625 influenza-like illness episodes; 987 confirmed positive by reverse transcription PCR (RT-PCR); 5464 were RT-PCR-negative.
  • 356 IIV4-vaccinated children and 693 controls had RT-PCR-confirmed influenza.
  • Moderate-to-severe illness was 41% less common with IIV4 vaccination (crude OR=0.59; 95% CI, 0.44-0.77).
  • Symptom frequency/duration was similar in both groups except for a lower prevalence of fever >39 ºC in IIV4-vaccinated children (17.7% [95% CI, 13.8%-22.1%] vs 28.30% [95% CI, 25.0%-31.9%]).
    • Crude OR=0.54; 95% CI, 0.39-0.75.
  • IIV4-vaccinated children had lower odds of breakthrough influenza (crude OR=0.59; 95% CI, 0.44-0.77).

Study design

  • Exploratory analysis of phase 3, multicentre trial data to assess influenza clinical presentation in children ages 6-35 months without risk factors, effect of IIV4 vaccination on outcomes.
  • Funding: GlaxoSmithKline.

Limitations

  • True vaccine effect underestimated.
  • Seasonal strains variations, population susceptibility to circulating strains unmeasured.