Vaccines have been seen as the most important solution for ending the COVID-19 pandemic. The aim of this study is to evaluate the antibody levels after inactivated virus vaccination. We included 148 healthcare workers (74 with prior COVID-19 infection and 74 not). They received with two doses of inactivated virus vaccine (CoronaVac). Serum samples were prospectively collected three times (Day 0, 28, 56). We measured SARS-CoV-2 IgG Spike-RBD antibodies quantitatively and neutralizing antibodies. After the first dose, antibody responses did not develop in 64.8% of the participants without prior COVID-19 infection. All participants had developed antibody responses after the second dose. We observed that IgGsp antibody titers elicited by a single vaccine dose in participants with prior COVID-19 infection were higher than after two doses of vaccine in participants without prior infection (geometric mean titer (GMT): 898 AU/ml, 607 AU/ml). IgGsp antibodies, participants with prior COVID-19 infection had higher antibody levels at all time points (p<0.001). We also found a positive correlation between IgGsp antibody titers and neutralizing capacity ( rs=0.697, p< 0.001). While people without prior COVID-19 infection should complete their vaccination protocol, the adequacy of a single dose of vaccine is still in question for individuals with prior COVID-19. New methods are needed to measure the duration of protection of vaccines and their effectiveness against variants as the world is vaccinated. We believe quantitative IgGsp values may reflect the neutralization capacity of some vaccines.
Fuente: Journal of Medical Virology
First published: 01 September 2021