Fourth dose fares well - for full Pfizer or half a Moderna shot

Embargoed until: Publicly released: 2022-05-10 08:30

International

A fourth dose of COVID-19 mRNA vaccines is well-tolerated and boosts the immune response compared to a third dose, finds a first-of-its-kind trial. In the study, 166 healthy adults who had received a third Pfizer dose (following either Pfizer or AstraZeneca first doses) were randomised to receive either full-dose Pfizer or half-dose Moderna as a fourth vaccine. The authors say peak immune responses after the fourth dose were similar to, and possibly better than, peak responses after the third dose. The half-shot of Moderna appeared to spark a higher immune response than a full Pfizer dose, but the team says the small sample means more research is needed to compare these.

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Research Elsevier, Web page

Journal/
conference: Lancet Infectious Diseases

Research:Paper

Organisation/s: COV-BOOST trial: including NIHR Southampton Clinical Research Facility and Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust, NIHR Oxford Biomedical Research Centre, Stockport NHS Foundation Trust, Nuffield Department of Medicine, Imperial College London, University of Southampton, University of Oxford, NIHR Liverpool and Broadgreen Clinical Research Facility, NIHR Cambridge Clinical Research Facility, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK - etc.

Funder: UK Vaccine Task Force and National Institute for Health Research.

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