The effect of the Toll-like receptor 7 agonist imiquimod before intradermal (ID) or intramuscular (IM) influenza vaccine in immunocompromised hosts is unknown.
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.
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.
In our study, topical imiquimod did not improve the immunogenicity of influenza vaccine in KT and in PLWH.