Forty-five participants had third shots of the vaccine as booster shot and were followed up till about one month after the third shot or 10 months after the first shots. Table?1 Participant characteristics. =0.0003, Wilcoxon test; NAb: =0.002, Wilcoxon test) and at the second doses BRAF inhibitor (TP6 vs TP2: TAb =0.0003, Wilcoxon test; NAb: =0.8116, paired t-test) ( Figures?2A, B ). Additionally, hematology analyses were performed. Results Pylon antibody testing revealed that every participant tested negative at the beginning, and 88.2% of them tested positive about 14 days after receiving their second dosage. The TAb levels and NAb levels peaked in 76.5% and 88.2% of the subjects, respectively, at the same time. Age was connected with the peak antibody levels, but not with gender, BMI, or baseline hematological factors. The positive rates and the antibody levels had already started to decline three months following the second injection. The antibody levels and avidities quickly increased following the booster doses to levels that were considerably greater than the ITGAV peak antibody responses before to the booster shots. Hematology testing revealed no safety concerns with immunizations. Conclusion In healthy workers, the two doses of BBIBP-CorV were able to induce humoral immunity; however, 3 months following vaccination, the antibody levels started to decline. The BBIBP-CorV booster injections increase both the quantity and quality of antibodies, which gave support for utilizing booster doses to prolong the duration of the vaccines protective effects. Keywords: antibody, booster shots, SARS-CoV-2, BBIBP-CorV, vaccine Introduction Since its initial discovery in December 2019, the coronavirus disease (COVID-19) has been a global pandemic (Zhou et?al., 2020). SARS-CoV-2, the causative agent of the disease, is a virus of the genus Betacoronavirus closely related to the SARS-CoV which was discovered in 2002 and also caused severe acute respiratory syndromes (Wu et?al., 2020). Due to COVID-19s high mortality rate during the start of the pandemic, there have been widespread attempts from many different disciplines to treat and control the disease. Among them, vaccines were the main strategy taken to stop the viruss spread and stop COVID-19 victims from developing severe cases and dying. Over thirty vaccines have been approved and used by countries around the world, which were based on different BRAF inhibitor vaccine platforms and technologies including mRNA vaccines, adenoviral vector-based vaccines, recombinant protein vaccines and inactivated virus vaccines (Piccaluga et?al., 2022). The Sinopharm inactivated viral vaccine BBIBP-CorV was widely utilized in mainland China. Observations of the immunogenicity of BBIBP-CorV and its protectiveness against infection, severe illness development, and mortality by these vaccines were made after two doses of BBIBP-CorV in pre-marketing clinical trials (Al Kaabi et?al., 2021; Xia et?al., 2021; Xia et?al., 2022) and real-world studies (Zhang et?al., 2021; Ismail AlHosani et?al., 2022). However, a booster shot has been recommended to increase protection against BRAF inhibitor the ongoing spread and recurring infections caused by SARS-CoV-2. The results of the longitude studies on the antibody responses in healthy subjects from the baseline to the booster doses show that the booster doses are efficacious. In this study, we assessed the maturation of antibody avidity following first-time BBIBP-CorV vaccination and reported the kinetics of antibody responses in healthcare professionals who received three doses of the vaccine over a period of 10 months. Materials and methods Study design and participants Eighty-five healthcare workers eligible to receive the inactivated SARS-COV-2 vaccine (BBIBP-CorV, Sinopharm, Beijing, China) were prospectively enrolled. All the participants completed vaccinations by administering two doses of the vaccine 1 month apart. Blood samples were collected on the day of the first and second shots of the vaccines, as well as one month, three months and 6 months after the second shot from each participant. Forty-five out of the eighty-five participants had the third shots of the vaccine, the booster shots, approximately 10 months after the first shots. For those forty-five participants, additional blood samples were also collected approximately one month after the booster shots. EDTA anti-coagulated whole blood samples were used for analysis by a hematology analyzer and a flow cytometry within 24 hours. Serum samples were prepared by centrifugation and stored at -80C.