Oxford vaccine dosing error led to an accidental success
A dosing error during clinical trials led to the Oxford vaccine reaching 90 per cent efficacy by accident, it has emerged.
In the spring, scientists were left baffled as to why participants were experiencing much milder side effects than expected. When they checked, they found that they had received just half the dose given to 500 adults in earlier safety trials. Instead of restarting the trial, researchers at Oxford University boosted the initial participants with a full dose while everyone who enrolled later received the full amount.
Trial results announced yesterday show that the ‘‘correct’’ vaccine dose achieved just 62 per cent efficacy while the ‘‘accidental’’ dose was 90 per cent effective. ‘‘The reason we had the half-dose is serendipity,’’ said Mene Pangalos, a vice president of AstraZeneca, the vaccine manufacturer. ‘‘We went back and checked . . . and we found out that they had underpredicted the dose of the vaccine by half.’’
Once informed, regulators allowed the trial of more than 20,000 volunteers to continue – leading to results which were last night hailed by the UK prime minister as ‘‘incredibly exciting news’’.
Professor Jonathan Van-Tam,
Britain’s deputy chief medical officer, yesterday said he shared ‘‘the euphoria’’ of scientists now that a third major vaccine had been shown to work.
AstraZeneca said 20 million doses could be available by the start of next year – with four million already waiting for use. The findings about the efficacy of the half-doses mean there could be enough for eight million people to begin their vaccination programme before Christmas.
In addition, up to five million doses of vaccines by Pfizer could be administered next month. Unlike the Pfizer jab, the vaccine from AstraZeneca can be kept at normal fridge temperatures, making it easier to store and distribute. Ministers hope that both jabs could begin being rolled out next month, with the NHS on standby to be ready to start administering vaccines from December 1.
The Medicines and Healthcare products Regulatory Agency is expected to be asked to begin assessing the AstraZeneca vaccine within days.
‘‘The reason we had the half-dose is serendipity.’’ Mene Pangalos AstraZeneca