In order to compare the immunogenicity and safety of different doses of trivalent influenza vaccine (TIV) administered intradermallly (ID) with those evoked by a full dose of intramuscular (IM) virosomal-adjuvanted influenza vaccine (VA-TIV), 112 previously primed healthy children aged ≥3 years were randomised to receive 9 μg or 15 μg of each strain of ID-TIV, or a full IM dose (15 μg of each strain) of VA-TIV. The A/H1N1 and A/H3N2 seroconversion and seroprotection rates were ≥90% and geometric mean titres (GMTs) increased 3.2-14.9 times without any statistically significant between-group differences; however, the seroconversion and seroprotection rates against the B strain were significantly higher in the children receiving either ID-TIV dose (p<0.05) without any differences between them. GMT against B virus was significantly higher in the children receiving the highest dose (p<0.05). Local reactions were significantly more common among the children receiving either ID-TIV dose (p<0.05), but systemic reactions were relatively uncommon in all three groups. Our findings suggest that ID-TIV with 15 μg of each viral antigen can confer a significant better protection against influenza than that obtained with the same dose of IM TIV in already primed children aged ≥3 years with an acceptable safety profile. The lower dose of ID-TIV needs further evaluation to analyze persistence of protection.
- Influenza vaccination
- Intradermal influenza vaccine
ASJC Scopus subject areas
- Immunology and Microbiology(all)
- Infectious Diseases
- Public Health, Environmental and Occupational Health
- Molecular Medicine