Abstract

Background: Inactivated SARS-CoV-2 vaccines have been widely implemented in low- and middle-income countries. However, immunogenicity in immunocompromised patients has not been established. Herein, we aimed to evaluate immune response to CoronaVac vaccine in these patients. Methods: This prospective cohort study included 193 participants with five different immunocompromising conditions and 67 controls, receiving two doses of CoronaVac 8-12 weeks before enrollment. The study was conducted between May and August 2021, at Red de Salud UC-CHRISTUS, Chile. Neutralizing antibodies (NAb) positivity, total anti-SARS-CoV-2 IgG antibodies (TAb) concentration, and T cell response were determined. Results: NAb positivity and median neutralizing activity were 83.1% and 51.2% for the control group versus 20.6% (p<0.0001) and 5.7% (p<0.0001) in the solid organ transplant (SOT) group, 41.5% (p<0.0001) and 19.2% (p<0.0001) in the autoimmune rheumatic diseases group, 43.3% (p=0.0002) and 21.4% (p=0.0013) in the cancer patients with solid tumors group, 45.5% (p<0.0001) and 28.7% (p=0.0006) in the HIV infected group, 64.3% (p=n.s.) and 56.6% (p=n.s.) in the hematopoietic stem cell transplantation (HSCT) group, respectively. TAb seropositivity was also lower for the SOT (20.6%, p<0.0001), rheumatic diseases (61%, p=0.0001) and HIV groups (70.9%, p=0.0032), compared to control group (92.3%). On the other hand, the number of IFN-y Spot Forming T Cells specific for SARS-CoV-2 tended to be lower but did not differ significantly between groups. Conclusions: Diverse immunocompromising conditions markedly reduce the humoral response to CoronaVac vaccine. These findings suggest a boosting vaccination strategy should be considered in these vulnerable patients.