Direct and total effectiveness of the intranasal, live-attenuated, trivalent cold-adapted influenza virus vaccine against the 2000-2001 influenza A(H1N1) and B epidemic in healthy children.
BACKGROUND
The efficacy of the intranasal, live-attenuated, trivalent cold-adapted influenza virus vaccine (CAIV-T) against influenza A(H3N2) and B infections in healthy persons is established, but its effectiveness against natural influenza A(H1N1) infection is unknown.


OBJECTIVE
To assess the effectiveness of CAIV-T in healthy children during the 2000-2001 influenza A(H1N1) and B epidemic.


METHODS
Community-based, nonrandomized, open-label trial from August 1998 through April 2001.


METHODS
Intervention and comparison communities in central Texas.


METHODS
Healthy children, aged 1.5 to 18 years, from the intervention communities received a single dose of CAIV-T at least 1 time or more in 1998, 1999, and/or 2000.


METHODS
The incidence of medically attended acute respiratory illnesses during the 2000-2001 influenza epidemic was compared in 3794 health plan CAIV-T recipients with age-eligible, health plan nonrecipients in the intervention communities for direct effectiveness (n = 9325), and with those in the 2 comparison communities for total effectiveness (n = 16,264).


RESULTS
The 2281 CAIV-T recipients in 2000 had significant direct protection against medically attended acute respiratory illness of 18% to 20% during the biphasic influenza A(H1N1) and B epidemic, and 17% to 26% during influenza A(H1N1) predominance. The 931 recipients of CAIV-T in 1999 containing influenza A/Beijing/262/95(H1N1) and B/Beijing/184/93-like viruses had persistent heterovariant protection against the 2000-2001 influenza A/New Caledonia/20/99(H1N1) and B/Sichuan/379/99 variants. The 616 recipients of a single CAIV-T dose in 1999 only, including those younger than 5 years with no prior natural exposure to influenza A(H1N1) viruses, showed persistent protection.


CONCLUSIONS
Healthy children who received CAIV-T in 2000 or 1999 were protected against new variants of influenza A(H1N1) and B in the 2000-2001 influenza epidemic.
Gaglani
Manjusha J
MJ
Section of Pediatric Infectious Diseases, Department of Pediatrics, Scott & White Memorial Hospital and Clinic, The Texas A&M University System Health Science Center College of Medicine, Temple, 76508, USA. mgaglani@swmail.sw.org
Piedra
Pedro A
PA
Herschler
Gayla B
GB
Griffith
Melissa E
ME
Kozinetz
Claudia A
CA
Riggs
Mark W
MW
Fewlass
Charles
C
Halloran
M Elizabeth
ME
Longini
Ira M
IM
Glezen
W Paul
WP
D000208:Acute Disease; D000281:Administration, Intranasal; D000293:Adolescent; D001741:Black or African American / Q000706:statistics & numerical data; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D004196:Disease Outbreaks / Q000517:prevention & control*; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D009980:Influenza A virus / Q000276:immunology*; D009981:Influenza B virus / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage*; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D012140:Respiratory Tract Diseases / Q000453:epidemiology; D013781:Texas / Q000453:epidemiology; D014611:Vaccination; D044465:White People / Q000706:statistics & numerical data
D007252:Influenza Vaccines