Antibody response to inactivated COVID-19 vaccine (CoronaVac) in immune-mediated diseases: a controlled study among hospital workers and elderly

Objective To assess antibody response to inactivated COVID-19 vaccine in patients with immune-mediated diseases (IMD) among hospital workers and people aged 65 and older. Methods In this cross-sectional study, we studied 82 hospital workers with IMD (mean age: 42.2 +/- 10.0 years) and 300 (mean age: 41.7 +/- 9.9 years) controls. Among + 65 aged population, we studied 22 (mean age: 71.4 +/- 4.5 years) patients and 47 controls (mean age: 70.9 +/- 4.8 years). All study subjects had a negative history for COVID-19. Sera were obtained after at least 21 days following the second vaccination. Anti-spike IgG antibody titers were measured quantitatively using a commercially available immunoassay method. Results Patients with IMD were significantly less likely to have detectable antibodies than healthy controls both among the hospital workers (92.7% vs 99.7%, p < 0.001) and elderly population (77.3% vs 97.9%, p = 0.011). Among patients with IMD, those using immunosuppressive or immune-modulating drugs (64/75, 85.3%) were significantly less likely to have detectable antibodies compared to those off treatment (29/29, 100%) (p = 0.029). Additionally, a negative association between age and the antibody titer categories among patients (r = - 0.352; p < 0.001) and controls (r = - 0.258; p < 0.001) were demonstrated. Conclusions Among hospital workers, the vast majority of patients with IMD and immunocompetent controls developed a significant humoral response following the administration of the second dose of inactivated COVID-19 vaccine. This was also true for the elderly population, albeit with lower antibody titers. Immunosuppressive use, particularly rituximab significantly reduced antibody titers. Antibody titers were significantly lower among those aged >= 60 years both in patient and control populations. Whether these individuals should get a booster dose warrants further studies.

Automated summary

Patients with immune-mediated diseases had lower antibody response to the inactivated COVID-19 vaccine compared to healthy controls, especially those using immunosuppressive or immune-modulating drugs. Older age was also associated with lower antibody titers in both patient and control populations. Further studies are needed to determine if booster doses are necessary for these individuals.