This was a Phase IV open label and single arm study, with the aim of enrolling up to 55 healthy males and non-pregnant females in a single site, age 18-49 years old, inclusive. This study was designed to assess the humoral response to influenza vaccination and the longevity of humoral immunity to influenza vaccination in healthy adults. Total enrollment was 27 participants.
The laboratory technique used in this study characterized persistence and clonotype of antigen specific B-cells and plasmablasts in blood and bone marrow. Enrolled participants received licensed seasonal inactivated influenza vaccine (administered as a part of the study). The vaccine was administered according to the package insert, and study participants donated serial samples of blood and bone marrow aspirate for immunology monitoring.
Safety was assessed from the time of study enrollment through the last study visit, via monitoring of vital signs, change in health status, and targeted physical exam with safety labs prior to each bone marrow aspirate procedure. Repeated measurements of humoral immunity were obtained at 7 days, 14 days, 28 days, 90 days and at one year post-vaccination to assess the magnitude, clonal diversity and persistence of B-cell responses to influenza vaccination.
This was a multi-year study. After one year of participation, participants were offered the opportunity to participate in the study for up to 3 consecutive years, provided eligibility criteria was met each year. Participants who elected to continue in the study after first year of participation were rescreened to verify continued eligibility and re-consented prior to subsequent participation.
Re-enrolling participants received new subject identifiers and will count towards the total enrollment number for subsequent years of participation. A separate subject record will be maintained each year a subject re-enrolls in the study. Enrollment for the next year will begin with the availability of the seasonal flu vaccine. For participants who elect to re-enroll in the study, the Day 365 visit (+/- 3 month window) would also be the Day 0 visit for the subsequent year. The primary study objective is to investigate the longevity of humoral immunity to influenza virus in humans. The secondary study objective is the longitudinal tracking of vaccine-induced B cell responses with special emphasis on broadly neutralizing HA (hemagglutinin) stem-reactive responses.
Note: Due to the Coronavirus Disease of 2019 (COVID-19) pandemic, all non-essential research was halted in mid-March 2020. New enrollments were placed on hold for this study. Follow-up visits were also halted, which impacted the timing of participants' subsequent follow-up visits. Participant visits for Day 7 and Day 14 were not impacted. For this study, there are participants whose Day 28 and Day 90 visits were impacted by the temporary halting of non-essential research studies. As such, a request was submitted to the Emory University Institutional Review Board to extend the missed visit windows for the Day 28 and Day 90 visits for a maximum of up to 180 days, to ensure that ample time was available to bring participants back for their missed visits. Enrollment for this study ended on March 31, 2020, before research activities could resume at Emory.
