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Immunogenicity of a Third Dose of BNT162b2 to Ancestral Severe Acute Respiratory Syndrome Coronavirus 2 and the Omicron Variant in Adults Who Received 2 Doses of Inactivated Vaccine.
- Source :
- Clinical Infectious Diseases; 2/1/2023, Vol. 76 Issue 3, pe299-e307, 9p
- Publication Year :
- 2023
-
Abstract
- Background Limited data exist on antibody responses to mixed vaccination strategies that involve inactivated coronavirus disease 2019 (COVID-19) vaccines, particularly in the context of emerging variants. Methods We conducted an open-label trial of a third vaccine dose of a messenger RNA (mRNA) vaccine (BNT162b2, Fosun Pharma/BioNTech) in adults aged ≥30 years who had previously received 2 doses of inactivated COVID-19 vaccine. We collected blood samples before administering the third dose and 28 days later and tested for antibodies to the ancestral virus using a binding assay (enzyme-linked immunosorbent assay [ELISA]), a surrogate virus neutralization test (sVNT), and a live virus plaque reduction neutralization test (PRNT). We also tested for antibodies against the Omicron variant using live-virus PRNT. Results In 315 participants, a third dose of BNT162b2 substantially increased antibody titers on each assay. Mean ELISA levels increased from an optical density of 0.3 to 2.2 (P <.001), and mean sVNT levels increased from an inhibition of 17% to 96% (P <.001). In a random subset of 20 participants, the geometric mean PRNT<subscript>50</subscript> titers rose substantially, by 45-fold from day 0 to day 28 against the ancestral virus (P <.001) and by 11-fold against the Omicron variant (P <.001). In daily monitoring, post-vaccination reactions subsided within 7 days for more than 99% of participants. Conclusions A third dose of COVID-19 vaccine with an mRNA vaccine substantially improved antibody levels against the ancestral virus and the Omicron variant with a well-tolerated safety profile in adults who had received 2 doses of inactivated vaccine 6 months earlier. Clinical Trials Registration NCT05057182. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 10584838
- Volume :
- 76
- Issue :
- 3
- Database :
- Complementary Index
- Journal :
- Clinical Infectious Diseases
- Publication Type :
- Academic Journal
- Accession number :
- 161829683
- Full Text :
- https://doi.org/10.1093/cid/ciac458