Immunogenicity of a third dose of BNT162b2 to ancestral SARS-CoV-2 & Omicron variant in adults who received two doses of inactivated vaccine.
Clin Infect Dis
; 2022 Jun 08.
Article
in English
| MEDLINE | ID: covidwho-2232402
ABSTRACT
BACKGROUND:
Limited data exist on antibody responses to mixed vaccination strategies involving inactivated COVID-19 vaccines, particularly in the context of emerging variants.METHODS:
We conducted an open label trial of a third vaccine dose of an mRNA vaccine (BNT162b2, Fosun Pharma/BioNTech) in adults aged ≥30 years who had previously received two 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 (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 (OD) of 0.3 to 2.2 (p < 0. 001), and mean sVNT levels increased from an inhibition of 17% to 96% (p < 0.001). In a random subset of 20 participants, the geometric mean PRNT50 titers rose very substantially by 45 fold from Day 0 to Day 28 against the ancestral virus (p < 0.001) and rose by 11 fold against the Omicron variant (p < 0.001). In daily monitoring, post-vaccination reactions subsided within 7 days for over 99% of participants.CONCLUSIONS:
A third dose of COVID-19 vaccination with an mRNA vaccine substantially improved antibody levels against the ancestral virus and the Omicron variant with well-tolerated safety profile, in adults who had received two doses of inactivated vaccine 6 months earlier.
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Type of study:
Randomized controlled trials
Topics:
Vaccines
/
Variants
Language:
English
Journal subject:
Communicable Diseases
Year:
2022
Document Type:
Article
Affiliation country:
Cid
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