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Around 1,500 Oxford Covid vaccine trial volunteers given wrong dose, weren't informed, reveals letter



01 Feb 2021

About 1,500 of the initial volunteers in a late-stage clinical trial of the Oxford/AstraZeneca Covid-19 vaccine were given the wrong dose, but weren't informed that a mistake had been made after the blunder was discovered, documents obtained by Reuters show.

Instead, the dosing mishap was presented to the trial participants in a letter dated June 8 as an opportunity for University of Oxford researchers to learn how well the vaccine works at different doses. The letter was signed by the trial's chief investigator, Oxford professor Andrew J. Pollard, and sent to the trial subjects.

As Reuters reported on Dec. 24, participants were given about a half dose due to a measuring mistake by Oxford researchers. The Pollard letter didn't acknowledge any error. Nor did it disclose that researchers had reported the issue to British medical regulators, who then told Oxford to add another test group to receive the full dose, in line with the trial's original plan.

There is no suggestion there was any risk to the health of trial participants.

Much is riding on the British-developed vaccine, which is being rolled out across the UK and has been touted as a low-cost weapon against the pandemic. The jab has come under scrutiny because of the dosing error in the Oxford trial and a paucity of data about its efficacy in older people who are most vulnerable to the virus.

Reuters shared the letter - which it obtained from the university through a Freedom of Information request - with three different experts in medical ethics. The ethicists all said it indicates the researchers may not have been transparent with trial participants. Volunteers in clinical trials are supposed to be kept fully informed about any changes.