Short-Term Immunogenicity of Licensed Subunit RSV Vaccines in Residents of Long-Term Care Facilities (LTCF) Compared to Community-Dwelling Older Adults

Objectives: Phase 3 licensing trials for the recently approved respiratory syncytial virus (RSV) vaccines did not include many residents of long-term care facilities (LTCF). Our primary objective was to assess humoral immune responses in LTCF residents, aged 60 and older, to the RSV vaccines, and demonstrate noninferiority to antibody responses in community-dwelling (CD) adults who were representative of the phase 3 trial participants in whom the vaccines were highly efficacious.

Design: Prospective non-randomized intervention trial of RSV vaccines in LTCF residents.

Setting and participants: Research clinic and 2 LTCFs. Adults aged ≥60 years old, free of immunosuppression and planning to receive an RSV vaccine were eligible.

Methods: LTCF and CD participants received either the GSK or Pfizer RSV vaccine in equal numbers. Blood was collected before and 30 days after vaccination. Total immunoglobulin (Ig)G to the prefusion F protein of RSV group A (F_A) and B (F_B), and neutralizing activity were measured, and geometric mean titer (GMT) and geometric mean fold rise (GMFR) calculated. Intercurrent respiratory illnesses were tracked.

Results: A total of 76 LTCF residents and 76 CD adults were enrolled. Day 30 blood was unavailable from 3 residents and 3 had RSV infection and vaccination was deferred, leaving data for 76 CD and 70 LTCF adults for analysis. Serum IgG GMFR prefusion F_A (9.9 vs 12.5, P = .14), prefusion F_B (8.7 vs 11.0, P = .17) were not statistically different in CD and LTCF cohorts, respectively, and also equivalent for GMFR in viral neutralization titers (12.8 vs. 15.5, P = .32). As measured by GMT or GMFR, RSV vaccine responses of LTCF residents met noninferiority criteria compared with the CD cohort.

Conclusions and implications: This small immunobridging study demonstrates robust antibody responses to RSV vaccines in LTCF residents providing support for their use in this high-risk population.