Ambitious Interpretation of Results of the Oxford Vaccine Group’s Latest Paper
by Dr Clare Craig FRCPath On February 1st the Oxford Vaccine Group published their latest findings on the Oxford/AstraZeneca vaccine. While the findings are encouraging, the way they have been interpreted is questionable. The study is underpowered for the conclusions that are being drawn from it and there has been extensive data mining undertaken retrospectively in an attempt to draw more powerful conclusions. They concluded that in the vaccinated group two thirds fewer people were infected. Despite admitting that they did not study transmission, they still commented on it. The conclusions reached were the overall percentage testing positive was 54% lower “indicating the potential for a reduction of transmission”. The 54% figure was deduced from positivity including asymptomatic positives. This is not a reasonable conclusion to draw on two counts. They have assumed that asymptomatic positives are a major source of transmission and there is minimal evidence to support that assertion; and they failed to account for false positive test results. Asymptomatic positives were looked for only in the UK participants. They have not stated how often these people were tested, but it can be inferred that they were tested 10 times each on a weekly basis for follow up from day 22 to day 90. That is 82,070 tests. A remarkably low false positive rate of 0.16% would be ...
