Long-term Immunogenicity and Boostability of the 13-valent Pneumococcal Conjugate Vaccine Followed by the 23-valent Pneumococcal Polysaccharide Vaccine in Adults Receiving Immunosuppressive Therapy and Adults With HIV-3-year Follow-up of a Prospective Cohort Study.

BACKGROUND

The long-term immunogenicity of the 13-valent pneumococcal conjugate vaccine (PCV13) followed by the 23-valent pneumococcal polysaccharide vaccine (PPSV23) remains unclear among immunocompromised patients (ICPs).

METHODS

This 3-year follow-up of a previously reported prospective cohort study included people with human immunodeficiency virus (HIV) (PWH), patients on immunosuppressive therapy, and immunocompetent controls who received PCV13 followed by PPSV23 2 months later. IgG levels for all 24 vaccine serotypes were measured 3 years after PCV13 (M36). The primary outcome was the seroprotection rate (SPR) at M36, defined as IgG concentrations ≥1.3 μg/mL for 17/24 vaccine serotypes. To assess immunological memory, we measured rapid recall responses 7 days after a PCV20 booster vaccination among initial responders 2 months after the priming schedule (M4) who had sero-reverted at M36.

RESULTS

Between M4 to M36, SPRs dropped from 44% (22/50) to 9% (5/55) in PWH, from 55% (59/108) to 17% (22/131) in patients on immunosuppressive therapy and from 82% (14/17) to 42% (8/19) in controls. Rapid recall responses were observed in 40% (4/10) of PWH, 14% (2/14) of patients on immunosuppressive monotherapy, 22% (2/9) of patients on combination therapy, and 67% (2/3) of controls. Antibody levels increased significantly for 7/13 PCV20/PCV13-shared serotypes, but for none (0/7) of the PCV20/PPSV23-shared serotypes.

CONCLUSIONS

Only a minority of PWH and patients on immunosuppressive therapy and under half of controls remained seroprotected 3 years after vaccination. As rapid recall responses were limited to PCV serotypes, future research in ICPs should focus on expanded priming schedule with higher-valent PCVs such as PCV20.