The third announced successful COVID-19 vaccine will undergo a new global trial, as questions were raised over its effectiveness.
The Oxford University/AstraZeneca vaccine is the first of the three publicly successful vaccination trials that does not require storage at sub-zero temperatures, making it logistically the most convenient of the three for both healthcare workers and air freight carriers transporting to developing countries.
However, questions have now been raised over how the Oxford vaccine’s trials were conducted and reported upon.
This is due to the fact that the researchers initially reported their vaccine’s overall efficacy at around 70 per cent – lower than the other two previously announced vaccination trials, but above the 60 per cent efficacy rate required by international regulators for a licensed vaccine.
Like many of the currently proposed COVID-19 vaccines, the Oxford vaccine requires two doses.
However, a sub-set of fewer than 3,000 people in the trial were given a lower dose regime of one half-dose, followed by a full dose of the vaccine – originally by accident. For these participants, efficacy rose to 90 per cent.
Researchers had no explanation for the 90 per cent result in people given a half dose followed by a whole dose of the vaccine, instead of two whole doses in other arms of the trial, however external researchers have made note that age may be a factor, as no one in the low-dose trial group was aged over 55.
On Thursday, AstraZeneca said it would undertake a new global trial using the lower-dose regimen.
It believes the timeline for regulatory approval and rollout of the vaccine in the UK and Europe should not be affected, however analysts do not expect to see this vaccine get US regulatory approval until after trials are completed within the US.
So far, pharmaceutical companies Pfizer and Moderna have both announced experimental vaccines that have been trialled with over 90 per cent efficacy.
Earlier this month, Pfizer chief executive Dr Albert Bourla said its vaccination would “help bring an end to this global health crisis”.
The global rollout of a COVID-19 vaccine would serve as a lifeline to the global aviation industry, which has been decimated by the pandemic.