The team behind the Oxford University and AstraZeneca Covid vaccine may have to carry out another global trial after a dosing error improved the effectiveness of the results. During the first trial, some people were given half dose followed by a full dose, which helped to increase the efficacy of the vaccine and produce results of up to 90 per cent protection. The vaccine gained worldwide attention thanks to its relatively cheap production, allowing for distribution to developing countries, and the fact it can be stored at fridge temperature. AstraZeneca has insisted that any additional trials would not hold up regulatory approval in the UK. Questions raised over trial process Director of the Oxford Vaccine Group, Professor Andrew Pollard, told a press briefing last week that the findings from the trial had already met the ‘necessary statistical evidence as required by regulators’. Pollard added that further evidence should be available next month. However, questions have been raised over the original trial process after the overall efficacy was put at 70 per cent. A subset of less than 3,000 people in the UK were given a lower dose regime and the efficacy rose to 90 per cent. A two dose regime was given to 8,895 people, with the overall efficacy in this case amounting to 62 per cent. On Monday (23 November) the team announced a combined effectiveness of 70 per cent. Sir Mene Pangalos, AstraZeneca’s head of biopharmaceuticals R&D, also confirmed that no one taking part in the low dose trial was over the age of 55. This has led to concerns that the younger age may have been a contributing factor to the high success rate. New global trial AstraZeneca confirmed on Thursday (26 November) that it would undertake a new global trial using the lower dose regime. The timeline for approval by the regulatory body and rollout of the vaccine in the UK and Europe should not be affected. The UK Government has pre-ordered 100 million doses of the Oxford vaccine, which would be enough to immunise 50 million people. Lack of details Other scientists have expressed concerns regarding the lack of detail released by the company when its results were announced last week. The New York Times reported that AstraZeneca’s Sir Mene Pangalos had to defend the company over its handling of the testing and its public disclosures. Professor John Moore, of Weill Cornell Medical College, told the New York Times, that the press release raised more questions than it answered. Experts have noted that the two clinical trials were designed differently, yet analysis was pooled from both tests for the final assessment. US critics have also claimed that there was not enough ethnic diversity, general and age balance within the original trial to satisfy the US regulator for approval of distribution with the country.