Evaluation of seroconversion and booster effect of the bbibp-corv vaccine (Sinopharm) in health personnel of a private laboratory in Lima, Peru

Vaccines
against COVID-19 have different immune response mechanisms; one of them is the
humoral response, which may vary according to the type of vaccine. This study
evaluated the seroconversion rate and booster effect that the bbibp-corv
vaccine (Sinopharm) generated in a population of health workers with
seroconversion status vs. known infection before the first dose. A total of 268
health workers were studied, 147 not previously seroconverted/infected (NSI)
and 121 previously seroconverted/infected (PSI), who were vaccinated with two
doses of bbibp-corv separated in 21 days. The anti-S1 and anti-N antibodies
were determined before the first and second dose. After 21-30 days of the
second dose, anti S1, anti RBD antibodies were dosed, and the presence of
neutralizing antibodies was evaluated with cPass™. 2.72% of NSI patients did
not generate Anti S1, Anti N, Anti RBD, or neutralizing Antibodies by cPass™.
The humoral immune response was considerably higher in PSI patients than NSI,
both in anti S1, Anti N, Anti RBD, and cPass™ antibodies. Thus, 97.5% of NSI
patients seroconvert with two doses of bbibp-corv; however, the humoral immune
response on them was lower than the booster effect seen on PSI, which could be
related to its poor efficacy.