An analysis of antibody response following the second dose of CoronaVac and humoral response after booster dose with BNT162b2 or CoronaVac among healthcare workers in Turkey

Abstract

Limited data are available on the short‐ to midterm levels of antibodies to the CoronaVac vaccine and quantitative change in humoral response after homologous or heterologous booster doses. In this prospective cohort study, we evaluated the anti‐receptor‐binding domain (RBD) immunoglobulin G (IgG) levels after two doses of CoronaVac and heterologous/homologous booster administration among healthcare workers in a university hospital in Turkey. Quantitative anti‐RBD IgG antibody levels were measured at first and fourth months in 560 healthcare workers who had completed two doses of CoronaVac vaccine, and within 2 months after the third dose of CoronaVac or BNT162b2. Participants were asked to complete a questionnaire during the first blood draw. The seropositivity rate was 98.9% and 89.1%, and the median antibody level was 469.2 AU/ml and 166.5 AU/ml at first and fourth month, respectively. In the fourth month, a mean reduction of 61.4% ± 20% in antibody levels was observed in 79.8% of the participants. The presence of chronic disease (odds ratio [OR]: 1.76, 95% confidence interval [CI]: 1.15–2.69) and being in the 36–50 age group (OR: 2.11, 95% CI: 1.39–3.19) were identified as independent predictors for low antibody response. The antibody level increased 104.8‐fold (median: 17 609.4 vs. 168 AU/ml) and 8.7‐fold (median: 1237.9 vs. 141.4 AU/ml) in the participants who received BNT162b2 and CoronaVac, respectively. During the follow‐up, 25 healthcare workers (4.5%) were infected with severe acute respiratory syndrome coronavirus 2. Considering the waning immunity and circulating variants, a single booster dose of messenger RNA vaccine seems reasonable after the inactivated vaccine especially in risk groups.

Immunogenicity evaluation after BNT162b2 booster vaccination in healthcare workers

“…In over 3000 HCW subjects from an Italian hospital, infection after vaccination occurred in 0.5% subjects mostly asymptomatic with no predominance of a specific viral variant 19 . Somewhat similar results were obtained in a Turkish HCW cohort were 4.5% of vaccinated personel were infected with SARS-CoV-2 20 and the booster dose of CoronaVac was advised 21 .…”

Kinetics of the Neutralizing and Spike SARS-CoV-2 Antibodies following the Sinovac Inactivated Virus Vaccine Compared to the Pfizer mRNA Vaccine in Singapore

“…Studies clearly show the benefits of such a heterologous vaccination regimen. In a study [ 32 ] of 560 healthcare workers, median IgG S-Ab (Abbott) decreased from 473.6 AU/mL to 166.5 AU/mL from the first and fourth month after the second dose of inactivated virus vaccine, with a drop in seropositivity from 98.9% to 89.1%. After a booster dose of the mRNA and inactivated virus vaccine, S-Ab levels increased by 104.8-fold and 8.7-fold, respectively, a 14.2-fold increase in favor of mRNA vaccination compared to the inactivated virus vaccine.…”

Dynamics of Neutralizing Antibody and T-Cell Responses to SARS-CoV-2 and Variants of Concern after Primary Immunization with CoronaVac and Booster with BNT162b2 or ChAdOx1 in Health Care Workers

“…Homologous or heterologous COVID-19 prime-boost vaccinations are introduced and reported to improve the humoral and cellular immune responses [ 6 , 7 ]. A homologous third dose of CoronaVac demonstrated increased immune responses against SARS-CoV-2; however, immunogenicity was lower when compared to a heterologous prime-boost with BNT162b2 [ 8 , 9 , 10 , 11 , 12 ]. Heterologous prime-boost vaccination with an mRNA vaccine or a viral vector vaccine is widely used as a booster dose because it can induce a high immune response and higher antibody levels, which are likely to provide greater protection against infection, as well as to overcome the new VOCs when there is a lack of specific VOC COVID-19 vaccines [ 11 , 13 ].…”