The slowdown in the ongoing phase 3 clinical trials has caused AstraZeneca to deliver far fewer doses than promised by year-end, according to the company officials.
The delays in its clinical trial prompted the company to hold off manufacturing, said Pascal Soriot, Chief Executive Officer of AstraZeneca. Instead of 30 million doses of the vaccine AZD1222, the UK will only receive 4 million this year, informed the Vaccine Taskforce Chair, Kate Bingham.
For the phase 3 efficacy clinical trial to read out, enough participants would need to contract the novel coronavirus as they go about their daily lives to allow researchers to assess the AZ candidate’s ability to protect against infection compared with a placebo shot.
When AstraZeneca signed the UK contract, infection rates were on the rise in the general public. But the number of incidents dropped during the summer, slowing the trial’s progress. Now, with cases ticking upward again, the company expects to have data available by year-end, said Soriot.
Besides slower infection incidents, the AZ shot’s phase 3 was temporarily paused for more than a month after a trial participant developed a serious neurological illness. The trial got the go-ahead to resume in the US in late October.
Because of the trial delays, AZ’s projected timeline for a vaccine authorization was also extended to ensure the final product has a maximum shelf life as doses are rolled out in mass vaccination campaigns.
“AZ has already produced a bulk vaccine that’s kept at freezing temperatures. The shelf life clock starts ticking once that frozen drug substance moves into the formulation phase of production,” said Pam Cheng, the company’s head of operations and IT.
At this point, it’s better to keep the vaccine in that frozen state because it can be stored for longer. After getting positive data from clinical trials, AZ can start “massively filling vials, and we’ll be ready to supply hundreds of millions of doses starting January next year,” said Soriot.
AstraZeneca has signed multiple deals to supply more than 3 billion doses of its candidate vaccine to countries around the world. On top of the 100 million doses it has promised the UK government, AZ has a contract to provide 300 million doses to the US and another with the EU for 400 million doses. In Japan, the company has agreed to deliver 120 million doses. In China, the vaccine will be offered by local firm BioKangtai, which will reserve enough capacity to make at least 100 million doses by the end of 2020.