Background: Heterologous COVID-19 booster vaccination is an alternative strategy to homologous vaccination, especially in developing countries, due to shortages, delays, or unequal distribution of COVID-19 vaccines. We compared cohorts vaccinated with different vaccine combinations to investigate whether a heterologous booster dose of mRNA-based BNT162b2 vaccine boosts the immune response in individuals primed with the CoronaVac vaccine.
Methods: Anti-RBD IgG is generally measured 4 weeks after primary immunization and 4 weeks after booster vaccination. Data on anti-receptor-binding domain (anti-RBD) IgG antibody titers and clinical characteristics were provided by infection control units.
Results: The highest median anti-RBD IgG antibody titers (14589 AU/mL) after primary immunization was observed in the group vaccinated with two doses of BNT162b2 vaccine. Antibody titers were lower 4 months or more after the second CoronaVac vaccine dose in CoronaVac recipients with or without previous COVID-19. In the homologous COVID-19 booster vaccine group (primed with two doses of CoronaVac 4 weeks apart and a single booster dose of CoronaVac) the median anti-RBD titers decreased from 1025 to 242 AU/mL before the booster dose. In the heterologous group (primed with two doses of CoronaVac 4 weeks apart and a single booster dose of BNT162b2), the median anti-RBD titer increased to 31624 AU/mL, a 132-fold increase, 16 days after the booster dose.
Conclusions: After the second dose of CoronaVac, protective neutralizing antibody levels decrease over time, and a booster dose is required. Heterologous COVID-19 booster vaccination with BNT162b2 is effective at boosting neutralizing antibody levels.
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http://dx.doi.org/10.1590/0037-8682-0046-2023 | DOI Listing |
J Med Virol
February 2025
Key Laboratory of Artificial Organs and Computational Medicine in Zhejiang Province, Shulan International Medical College, Zhejiang Shuren University, Hangzhou, Zhejiang, P. R. China.
Immunity against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) can be induced through either infection with the virus or vaccination, providing protection against reinfection or reducing the risk of severe clinical outcomes. In this study, we recruited 172 volunteers who received different vaccination regimens, including 124 individuals who had recovered from breakthrough infections caused by the Omicron variant (27 with 2 doses, 49 with 3 doses, and 48 with 4 doses) and 48 healthy donors who did not experience breakthrough infections (all of whom received a fourth dose during the infection wave). We measured neutralizing antibody levels against Omicron BA.
View Article and Find Full Text PDFHum Vaccin Immunother
December 2025
Crucell Integration, Janssen Research and Development, Beerse, Belgium.
We conducted a randomized, Phase 2 trial to assess the safety and humoral immunogenicity of reduced doses/dose volume of the standard dose of Ad26.COV2.S COVID-19 vaccine (5 × 10 viral particles [vp]) in healthy adolescents aged 12-17 years.
View Article and Find Full Text PDFObjectives: Patients with chronic lymphocytic leukaemia (CLL) have an increased risk of severe coronavirus disease 2019 (COVID-19) as well as impaired responses to COVID-19 vaccination, which may be overcome by repeated booster vaccinations. Our objective was to explore the uptake of the COVID-19 vaccine in this population since records of this are scarce.
Methods: In this nationwide cohort study, we used multiple population-based health and sociodemographic registries to study COVID-19 vaccine uptake in individuals with CLL in Sweden, from 27 December 2020 to 28 February 2023.
COVID-19 vaccination is the most effective strategy for preventing severe disease and death. Inactivated vaccines are the most accessible type of COVID-19 vaccines in developing countries. Several studies, including work from our group, have demonstrated that the third dose (booster vaccination) of inactivated COVID-19 vaccine induces robust humoral and cellular immune responses.
View Article and Find Full Text PDFExpert Rev Vaccines
December 2025
South Africa Medical Research Council Vaccines and Infectious Diseases Analytics Research Unit, University of the Witwatersrand, Faculty of Health Science, Johannesburg, South Africa.
Background: Due to high costs of pneumococcal conjugate vaccines (PCV), transitioning from a two (2 + 1) to a single dose (1 + 1) primary series with a booster should be considered. This study evaluated the immune response at 18 months of age following a 1 + 1 compared to a 2 + 1 schedule of 10-valent (PCV10) and 13-valent (PCV13) vaccines.
Research Design And Methods: A single-center, open-label, randomized trial conducted in Soweto, South Africa, evaluated the immunogenicity of differing dosing schedule for PCV10 and PCV13.
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