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Superior magnitude and durability of hybrid immunity following SARS-CoV-2 infection
Laimis Silimavicius1,2, Kacper Packi3,4, Mege Cerniauskiene3
1Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathum Thani, Thailand.
Background:
The emergence of the SARS-CoV-2 Delta variant necessitated examining hybrid immunity (vaccination- plus-infection) to optimize boosting strategies. We analyzed the kinetics, magnitude, and durability of anti-spike receptor binding domain immunoglobulin G (Anti-sRBD IgG) following Delta infection.
Objective:
This study analyzed the kinetics, magnitude, and long-term durability of anti-spike receptor binding domain immunoglobulin G (Anti-sRBD IgG) levels following Delta variant infection across individuals with diverse vaccination histories.
Methods:
This observational cohort study monitored 161 patients with varying vaccination histories for up to 16 weeks post-infection. Responses were compared against SARS-CoV-2 naïve controls receiving a two-dose inactivated series plus a heterologous booster. Sub-analyses assessed post-infection booster immunogenicity.
Results:
Prior vaccination significantly enhanced humoral responses. Patients with two prior doses achieved the highest median Anti-sRBD IgG peaks, surpassing vaccine-boosted naïve controls. While unvaccinated individuals exhibited delayed primary responses, hybrid immunity demonstrated superior durability with slower antibody decay than vaccine-only immunity. Crucially, while a post-infection booster effectively primed unvaccinated patients, early boosting in previously vaccinated individuals yielded minimal immunological gain.
Conclusions:
Prior vaccination significantly enhanced humoral responses. Patients with two prior doses achieved the highest median Anti-sRBD IgG peaks, surpassing vaccine-boosted naïve controls. While unvaccinated individuals exhibited delayed primary responses, hybrid immunity demonstrated superior durability with slower antibody decay than vaccine-only immunity. Crucially, while a post-infection booster effectively primed unvaccinated patients, early boosting in previously vaccinated individuals yielded minimal immunological gain.
