Immunoglobulin G and neutralizing antibody response after CoronaVac.

OBJECTIVE

The aim of this study was to evaluate the kinetics of immunoglobulin G and neutralizing antibody responses following vaccination with CoronaVac in healthcare professionals.

METHODS

A cohort of 35 healthcare professionals was recruited, and blood samples were collected to assess immunoglobulin G detection and neutralizing antibodies against severe acute respiratory syndrome coronavirus 2.

RESULTS

Immunoglobulin G seroconversion peaked at D30 (68.2%, 15/22), followed by stabilization at D48 and D90. Logistic regression confirmed a significant association between time post-vaccination and seroconversion (p=0.0043). Neutralizing antibody analysis showed a stable detection rate for Nab V1 (Wuhan and B.1.1.7) between D48 and D90 (p>0.9999), while Nab V2 (B.1.351 and P.1) remained consistently lower. Among immunoglobulin G-positive individuals, 92.3% (12/13) had neutralizing antibodies at D48, decreasing to 42.8% (6/14) at D90.

CONCLUSION

CoronaVac effectively induces immunoglobulin G seroconversion, peaking at D30. However, neutralizing responses to emerging variants were lower, suggesting the need for booster doses to maintain immunity. These findings highlight the importance of monitoring vaccine-induced immunity over time.