TABLE 4

Influenza VE for Prevention of Influenza A and B–Associated ED Visits Among Children by Using Influenza Vaccination Status Obtained by Parental Report, NVSN, 2018–2019

Influenza-Positive (Case Patients)Influenza-Negative (Non–Case Patients)VE
No. Vaccinated/Total%No. Vaccinated/Total%VE, % (95% CI)Adjusteda VE, % (95% CI)
All influenza viruses
 All ages170/42040878/15245850 (38 to 60)51 (38 to 62)
  6 mo to <5 y116/29040749/12685954 (40 to 64)55 (39 to 67)
  5–17 yb54/13042129/2565030 (−7 to 54)35 (−6 to 60)
A(H3N2) viruses96/20447878/15245835 (12 to 51)39 (15 to 56)
A(H1N1)pdm09 viruses54/14737878/15245857 (39 to 70)61 (44 to 73)
  • a Adjusted for study site, age as a continuous variable, race and/or ethnicity, and calendar time (monthly intervals).

  • b Children <18 y were enrolled in 4 of 7 NVSN sites: Cincinnati, Houston, Nashville, and Rochester; children <5 y only were enrolled in Kansas City, Pittsburgh, and Seattle.