Details

Autor(en) / Beteiligte

• Leung, Nancy H L
• Cheng, Samuel M S
• Martín-Sánchez, Mario
• Au, Niki Y M
• Ng, Yvonne Y
• Luk, Leo L H
• Chan, Karl C K
• Li, John K C
• Leung, Yonna W Y
• Tsang, Leo C H
• Chaothai, Sara
• Kwan, Kelvin K H
• Ip, Dennis K M
• Poon, Leo L M
• Leung, Gabriel M
• Peiris, J S Malik
• Cowling, Benjamin J

Titel

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

Ist Teil von

• Clinical infectious diseases, 2023-02, Vol.76 (3), p.e299-e307

Ort / Verlag

United States

Erscheinungsjahr

2023

Quelle

Oxford Journals 2020 Medicine

Beschreibungen/Notizen

• 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. 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. 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 PRNT50 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. 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. NCT05057182.