Reduced Immune Response to Inactivated Severe Acute Respiratory Syndrome Coronavirus 2 Vaccine in a Cohort of Immunocompromised Patients in Chile

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.