Drug major AstraZeneca has "voluntarily paused" a randomised clinical trial of its AZD1222 COVID-19 vaccine, which is considered as the frontrunner in the global race for an effective coronavirus vaccine. The British-Swedish company, which is developing the vaccine in collaboration with the University of Oxford, has temporarily halted phase 3 clinical trials of its COVID-19 vaccine candidate after a study participant developed severe adverse reactions.
Commenting on the development, AstraZeneca spokesperson said that this is a routine action which is taken whenever there is a potentially unexplained illness in one of the trials.
The spokesperson added that the company is working to expedite the review of the single event to minimise any potential impact on the trial timeline. The company is committed to the safety of its participants and the highest standards of conduct in its trials.
In phase 3, participants are being randomised to receive two doses of either AZD1222 or a saline control, four weeks apart, with twice as many participants receiving the potential vaccine than the saline control. The trial intends to assess efficacy and safety of the vaccine in all participants, and local and systemic reactions and immune responses in 3,000 participants.
The late-stage phase 3 clinical trial of AstraZeneca's COVID-19 vaccine is being conducted at various sites, including the United Kingdom, where the adverse event was reported. In the US, the company has started enrolling up to 30,000 volunteers adults aged 18 years or over to assess safety, efficacy and immunogenicity of AZD1222 for the prevention of COVID-19.
Clinical development of AZD1222 is progressing globally with late-stage clinical trials ongoing in the UK, US, Brazil and South Africa. The company has also planned to start tests in Japan and Russia. More than 50,000 participants have been enrolled to undergo final phase trials with AZD1222 COVID-19 vaccine, including about 30,000 in the US, more than 1,000 in India, Brazil and the UK. In India, Serum Institute of India is the partner to conduct the trials, currently progressing in about 17 trial sites, each with over 1,000 patients.
The clinical trials are being conducted at around 100 centres in and outside the US, including 62 study locations in the country. Results from the late-stage trials are anticipated later this year, depending on the rate of infection within the clinical trial communities.
In July 2020, interim results from the phase 1 and 2 COV001 trial showed AZD1222 was tolerated and generated robust immune responses against the SARS-CoV-2 virus in all evaluated participants, the company had said in a press statement.
By Chitranjan Kumar