Hybrid immunity augments cross-variant protection against COVID-19 among immunocompromised individuals.

Background: Immunity to SARS-CoV-2 vaccination and infection differs considerably among individuals. We investigate the critical pathways that influence vaccine-induced cross-variant serological immunity among individuals at high-risk of COVID-19 complications.

Methods: Neutralizing antibodies to the wild-type SARS-CoV-2 virus and its variants (Beta, Gamma, Delta and Omicron) were analyzed in patients with autoimmune diseases, chronic comorbidities (multimorbidity), and healthy controls. Antibody levels were assessed at baseline and at different intervals up to 12 months following primary and booster vaccination with either BNT162b2 or mRNA-1273. Immunity induced by vaccination with and without infection (hybrid immunity) was compared with that of unvaccinated individuals with recent SARS-CoV-2 infection. Plasma cytokines were analyzed to investigate variations in antibody production following vaccination.

Results: Patients with autoimmune diseases (n = 137) produced lesser antibodies to the wild-type SARS-CoV-2 virus and its variants compared with those in the multimorbidity (n = 153) and healthy groups (n = 229); antibody levels were significantly lower in patients with neuromyelitis optica and those on prednisolone, mycophenolate or rituximab treatment. Multivariate logistic regression analysis identified neuromyelitis optica (odds ratio 8.20, 95% CI 1.68-39.9) and mycophenolate (13.69, 3.78-49.5) as significant predictors of a poorer antibody response to vaccination (i.e, neutralizing antibody <40%). Infected participants exhibited antibody levels that were 28.7% higher (95% CI 24.7-32.7) compared to non-infected participants six months after receiving a booster vaccination. Individuals infected during the Delta outbreak generated cross-protective neutralizing antibodies against the Omicron variant in quantities comparable to those observed after infection with the Omicron variant itself. In contrast, unvaccinated individuals recently infected with the wild-type (n = 2390) consistently displayed lower levels of neutralizing antibodies against both the wild-type virus and other variants. Pathway analyses suggested an inverse relationship between baseline T cell subsets and antibody production following vaccination.

Conclusion: Hybrid immunity confers a robust protection against COVID-19 among immunocompromised individuals.