Excessive dosing of Pfizer COVID-19 vaccine a 'well-known risk', as Australia ramps up its vaccine rollout By medical reporter Sophie Scott and the Specialist Reporting Team's Alison Branley Posted ThuThursday 25 updated ThuThursday 25 Two elderly patients received too much of the Pfizer-BioNTech COVID-19 vaccine. ( Print text only Cancel The potential for giving the wrong dosage of the Pfizer vaccine is a well-known risk authorities should have been prepared for, a vaccination expert says. Key points: Nearly all vaccines used before now in Australia have come in single-dose vials One expert said the risk had to be weighed against the urgent need to get jabs into people's arms