Background: The effect of the Toll-like receptor 7 agonist imiquimod before intradermal (ID) or intramuscular (IM) influenza vaccine in immunocompromised hosts is unknown. Methods: In this open-label randomized controlled trial, kidney transplant recipients (KT) and people living with HIV (PLWH) were randomized to receive IM trivalent inactivated influenza vaccine alone (IM), IM vaccine after topical imiquimod (imi+IM) or ID vaccine after topical imiquimod (imi+ID). Immunogenicity was assessed by hemagglutination inhibition assay. The primary outcome was vaccine response, defined as seroconversion to at least one viral strain at day 21. Results: Seventy patients (35 KT and 35 PLWH) received IM (24), imi+IM (22), or imi+ID (24) vaccine. Vaccine response was 61% (14/23) with IM, 59% (13/22) with imi+IM, and 65% (15/23) with imi+ID vaccine (P = 0.909). Vaccine response was associated with HIV infection compared to kidney transplantation (adjusted-OR 3.74, 95% CI 1.25 – 11.23, P = 0.019), but not with imiquimod application nor ID injection. After vaccination, seroprotection to all viral strains was 79% (19/24) with IM, 68% (15/22) with imi+IM, and 70% (16/23) with imi+ID (P = 0.657). We did not observe any vaccine-related severe adverse event. Conclusions: In our study, topical imiquimod did not improve the immunogenicity of influenza vaccine in KT and in PLWH.
Bibliographical noteFunding Information:
This work was supported by the “Bourse de la relève 2016″ of the Leenaards Foundation awarded to OM.
OM reports grants from Lophius Biosciences, personal fees from MSD, personal fees from Gilead, outside the submitted work. MC reports grants from Gilead, MSD and Viiv, outside the submitted work paid to his institution. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest.
We thank all study participants. We are particularly grateful to Mrs Deolinda Alves for logistical and technical support during the whole study. We thank the Transplantation center outpatients? clinic staff for assistance during the study. This work was presented in part at the 28th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID), 21?24th April 2018, Madrid, Spain (Abstract P0037).
- Influenza vaccines