AstraZeneca Pauses Covid-19 Vaccine Trial Over Suspected Serious Adverse Reaction

The nature of the suspected serious adverse reaction is unknown, but the study participant is expected to recover.

KUALA LUMPUR, Sept 9 — A Phase 3 trial in the United States testing a coronavirus vaccine by AstraZeneca and the University of Oxford has been put on hold, after a participant in the United Kingdom was suspected to suffer a serious adverse reaction.

STAT reported AstraZeneca, a British-Swedish multinational pharmaceutical company, as saying in a statement that its “standard review process triggered a pause to vaccination to allow review of safety data” and that it had initiated pausing the study.

According to STAT, the participant suffering the adverse reaction, whose nature and severity are still unknown, is expected to recover.

The AstraZeneca spokesperson was quoted saying that the pause of the major clinical trial in the US — which started late last month and is currently taking place at 62 sites across the country (though some sites have not yet enrolled participants) — was “a routine action which has to happen whenever there is a potentially unexplained illness in one of the trials, while it is investigated, ensuring we maintain the integrity of the trials”. The Phase 3 trial in the US reportedly aims to enroll about 30,000 participants at 80 sites nationwide.

STAT reported that the AstraZeneca-Oxford Covid-19 vaccine candidate — a frontrunner in the global race for a vaccine against the novel coronavirus — was the first Phase 3 Covid-19 vaccine trial known to have been paused. There are reportedly nine coronavirus vaccine candidates in Phase 3 trials.

Clinical holds in ongoing studies, according to STAT, usually involve postponing the recruitment of new participants and giving doses to existing ones, unless it is deemed safe for study participants to continue receiving doses.

The AstraZeneca-Oxford vaccine — known as AZD1222 — uses an adenovirus that carries a gene for a protein in SARS-CoV-2; the adenovirus aims to induce the immune system in the human body to generate a protective response against the virus that causes the Covid-19 disease.

STAT reported a clear possibility that the adverse reaction occurred in the ongoing Phase 2/3 trial in the UK. Various reactions can be classified as a suspected serious adverse reaction — symptoms requiring hospitalisation, life-threatening illness, and death.

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