Methods: We conducted a prospective, randomized controlled, observer blind trial of HDTIV (60µg antigen/strain) versus SDTIV (15µg antigen/strain) in healthy HCWs 18-64yrs of age in November, 2014. The primary outcome was seroconversion to vaccine strains measured by change in HAI GMT from day 0 (pre-vaccine) to day 21 post-vaccination.
Results: 47 HCWs were enrolled; 37 were female; the median age was 40yrs (range 22-64yrs). 25 received HDTIV (24 with HAI results) and 22 SDTIV. There was no significant difference in pre-vaccination HAI GMTs. Post-vaccination HAI GMTs for vaccine strains were: for A(H3N2) 1092 HD v 405 SD, A(H1N1) 1337 HD v 601 SD, and B 2061 HD v 1165 SD (all p<0.01). Seroconversion rates for vaccine strains were: A(H3N2) 17/24 (71%) HD v 4/22 (18%) SD (p=.0004); A(H1N1) 13/24 (54%) HD v 7/22 (32%) SD (p=0.15); B 8/24 (33%) HD v 3/22 (14%) SD (p=0.17). No subject missed work or sought medical attention in the 7 days after vaccination. HCWs receiving HDTIV reported more site pain one day following vaccination (mean 3 v 1.6 on numeric [0-10] pain scale, p=0.03), but there was no other significant difference in local reactions. More HCWs receiving HDTIV reported a systemic reaction in the 7 days post-vaccination (16/25 v 7/22, respectively; p = 0.04). The most common systemic reactions were fatigue, malaise, muscle aches and headache. There was no difference in the rate of those who would accept vaccination with the same vaccine in the future (HD 22/25 v SD 20/22, p=1).
Conclusion: HCWs receiving HDTIV were more likely to seroconvert than those receiving SDTIV and day 21 HAI GMT were significantly higher. HDTIV was associated with an increased rate of injection site pain and systemic reactions, although this appeared not to influence acceptability. Further study of HD TIV efficacy in this group is warranted.
B. L. Coleman, Sanofi Pasteur: Investigator , Research support
K. Katz, None
A. E. Simor, None
M. P. Muller, None
J. Powis, None
J. Mcelhaney, Sanofi Pasteur: Investigator , Research support