No new adverse reactions were identified. Adverse reactions following Pfizer bivalent BA.4/5 as a second booster dose included pain at the injection site (68.5%), fatigue (56.4%), headache (41.4%), muscle pain (25.8%), chills (16.9%), joint pain (13.4%), fever (7.3%), injection site swelling (5.4%), injection site redness (4.8%), and lymphadenopathy (0.3%). The short term safety of the Pfizer bivalent BA.4/5 vaccine was shown to be similar to the previous Pfizer bivalent BA.1 and original vaccines when used as a booster. 9 A nationwide cohort study conducted in Nordic countries during July to December 2022 found VE against hospitalisation for a second booster of bivalent BA.4/5 vaccine of 80.5% (95%CI 69.5% to 91.5%) and for an original vaccine second booster of 64.9% (95%CI 57.7% to 72.2%), both relative to not receiving a second booster. 8,9 A US study showed vaccine effectiveness (VE) against hospitalisation or death with a bivalent BA.4/5 booster (either Pfizer or Moderna) was 61.8% (95% CI 48.2 to 71.8%) compared with an original booster VE of 24.9% (95%CI 1.4 to 42.8%). 6,7 Early published and preprint data on whether these increases in neutralisation activity translate into measurable differences in clinical protection suggest a small advantage in vaccine effectiveness with bivalent vaccines over original vaccines in preventing hospitalisation and death. 2-5 Two studies have found the neutralisation response to be similar between bivalent BA.4/5 and original vaccines. BQ.1, XBB) compared to the Pfizer original vaccine. 1 Similar trends were seen in 12-17 year and 18-55 year age groups.Īn additional four studies report higher neutralisation titres following a booster dose of Pfizer bivalent BA.4/5 vaccine for BA.4/5 and other sub-variants (e.g. The bivalent vaccine had non-inferior and modestly higher titres for ancestral strain neutralisation (GMR 1.38, 95%CI 1.22-1.56). Neutralisation of newer BQ.1.1 and XBB.1 subvariants was also higher than with the original vaccine. The Pfizer bivalent BA.4/5 vaccine is not currently registered for use in children aged 55 years who received the Pfizer bivalent BA.4/5 vaccine developed higher neutralising antibody titres to the BA.4/5 Omicron subvariant (geometric mean ratio 2.91, 95%CI 2.45-3.44) than those who received the Pfizer original vaccine. RecommendationsĪTAGI advises that the Pfizer bivalent BA.4/5 vaccine can be used as a booster dose by adolescents and adults aged ≥12 years who are recommended to receive a COVID-19 booster according to the ATAGI 2023 booster advice. ![]() ![]() ![]() The Australian Technical Advisory Group on Immunisation (ATAGI) has evaluated the immunogenicity, efficacy, and safety data on this vaccine. On 20 January 2023, the Therapeutic Goods Administration of Australia provisionally approved the Pfizer (Comirnaty) Bivalent Original/Omicron BA.4/5 vaccine (subsequently referred to as Pfizer bivalent BA.4/5) for use as a booster COVID-19 vaccine in people aged 12 years and older.
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