Comparison of immunogenicity and tolerability of a virosome-adjuvanted and a split influenza vaccine in children.
OBJECTIVE
To compare the immunogenicity and safety of a virosome-adjuvanted influenza vaccine (Inflexal V; Berna Biotech, Berne, Switzerland) and a split influenza vaccine (Fluarix; GlaxoSmithKline Biologicals, Rixensart, Belgium) in children.


METHODS
The subjects, 453 children ages 6 to 71 months, were stratified into primed and unprimed and age groups (6 to 35 and 36 to 71 months) and then randomized 1:1 to receive virosome-adjuvanted (n = 224) or split influenza vaccine (n = 229), a half or full dose was given intramuscularly according to age. Unprimed children received a second dose after 4 weeks. Blood samples (n = 326) collected pre-and 28 days postvaccination were analyzed by hemagglutination inhibition test. Safety assessments were made at baseline and follow-up visits by the investigators and by parents for the 4 days after vaccinations.


RESULTS
Both vaccines induced an effective immune response. Seroconversion rates (>4-fold titer rise) against the WHO recommended strains A/New Caledonia (H3N2), A/Moscow (H1N1) and B/Hongkong (B) were 80.1, 66.0 and 90.4% for the virosome-adjuvanted and 75.9, 62.9 and 89.4% for the split influenza vaccine, respectively. Unprimed children's seroconversion rates for H3N2 were significantly higher (P = 0.02) for the virosome-adjuvanted (88.8%) than for split influenza vaccine (77.5%). Seroprotection rates (titer of > 40) for H3N2, H1N1 and B, respectively, were 87.8, 80.1 and 90.4% after vaccination with the virosome-adjuvanted vaccine and 82.9, 78.2 and 89.4% after the split influenza vaccine. Unprimed children's seroprotection rate was significantly higher (P = 0.03) for H3N2 after the virosome-adjuvanted (88.8%) than those for the split influenza vaccine (78.3%). Equivalent geometric mean titer fold increases were evident for both vaccines. No serious adverse events were seen. Pain/ tenderness, redness and swelling/induration was found in 25.4, 11.2 and 8.9% for the virosome-adjuvanted vaccine and in 24.0, 9.2 and 6.1% for the split influenza vaccine, respectively. The rates of fever, malaise/irritability and shivering was 6.3, 11.6 and 2.7% for the virosome-adjuvanted vaccine and 8.3, 11.8 and 2.6% for the split influenza vaccine, respectively.


CONCLUSIONS
The virosome-adjuvanted influenza vaccine showed greater immunogenicity over the split influenza vaccine in unprimed children and showed a trend toward better immunogenicity in the rest of the study population. Both vaccines were well-tolerated.
Kanra
Güler
G
Hacettepe University, Ankara, Turkey.
Marchisio
Paola
P
Feiterna-Sperling
Cornelia
C
Gaedicke
Gerhard
G
Lazar
Hedvika
H
Durrer
Peter
P
Kürsteiner
Oliver
O
Herzog
Christian
C
Kara
Ates
A
Principi
Nicola
N
D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007109:Immunity / Q000502:physiology*; D007115:Immunization Schedule; D007223:Infant; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000009:adverse effects; D007251:Influenza, Human / Q000517:prevention & control*; D007273:Injections, Intramuscular; D008297:Male; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D015164:Vaccines, Inactivated / Q000008:administration & dosage* / Q000009:adverse effects; D022721:Vaccines, Virosome / Q000008:administration & dosage / Q000009:adverse effects
D007252:Influenza Vaccines; D015164:Vaccines, Inactivated; D022721:Vaccines, Virosome