Evaluating long-term antibody responses to booster doses of COVID-19 vaccines in the Pakistani population

Abstract

Background & Objective: Nearly 80 million of the Pakistani population received two doses of the BBIBP-CorV vaccine, against SARS-CoV-2, and 2.6 million people received heterologous booster doses up to February 2022. Our objective was to measure the long-term change of antibody titers in persons vaccinated with Pfizer–BioNTech COVID-19 following two doses of BBIBP-CorV.

Methods: Serum specimens from forty-three participants were collected 4-8 weeks following two doses of BBIBP-CorV at the Indus Hospital & Health Network, Karachi. A second set of serum specimens were collected 2-12 months after Pfizer–BioNTech COVID-19 booster dose administration. Chemiluminescent Microparticle Immunoassay (CMIA, Abbott Alinity Quant), and the pseudotyped lentivirus antibody neutralization assay were performed on all specimens. The latter assay was reported as log half-maximal inhibitory concentrations (IC50), calculated using a nonlinear regression algorithm (log [inhibitor] versus normalized response variable slope) in Graph Pad Prism 9. Paired sample t-test was used to ascertain the statistical significance of the difference in means of antibody titers obtained before and after the booster vaccine doses.

Results: Mean log10 values obtained with CMIA before and after the booster dose were 2.90 AU/mL and 3.87 AU/mL respectively, while the corresponding log10 IC50 values obtained through pseudotyped lentivirus antibody neutralization assay were 2.45 and 2.80. These differences were statistically significant with CMIA (p = <0.00001), but not with pseudotyped lentivirus antibody neutralization assay (p = 0.06318.).

Conclusion: A heterologous booster dose with Pfizer–BioNTech COVID-19 vaccine following two doses of BBIBP results in increased total antibody titers, though neutralizing antibody titers may start to wane a few months after the booster dose.

doi: https://doi.org/10.12669/pjms.40.2(ICON).8951

How to cite this: Hussain S, Naseer F, Kanani F, Aijaz J. Evaluating long-term antibody responses to booster doses of COVID-19 vaccines in the Pakistani population. Pak J Med Sci. 2024;40(2):S28-S34. doi: https://doi.org/10.12669/pjms.40.2(ICON).8951

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