AstraZeneca have put their trials on hold after a participant returned a serious reaction to their potential COVID vaccine.



The development of a Covid-19 vaccine being developed by AstraZeneca and the University of Oxford has been put on hold due to a suspected serious adverse reaction in a participant in the United Kingdom.

A spokesperson for AstraZeneca said in a statement that the company’s “standard review process triggered a pause to vaccination to allow a review of safety data.”

In a follow-up, the company said it put the study on hold. According to Stat News, “The nature of the adverse reaction and when it happened were not immediately known, though the participant is expected to recover, according to an individual familiar with the matter.”

The spokesperson described the pause as “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…(we are) working to expedite the review of the single event to minimize any potential impact on the trial timeline.”

While similar holds are not uncommon, it is unclear how long AstraZeneca’s might last. A study of the first and second phase was published in July, reporting that about 60% of 1,000 participants returned side effects. inclusive of fever, headaches, muscle pain, and injection site reactions, but were deemed mild or moderate. It was also noted that all of the reported side effects subsided during the course of the study.

Per Stat News, “The vaccine  — known as AZD1222 — uses an adenovirus that carries a gene for one of the proteins in SARS-CoV-2, the virus that causes Covid-19. The adenovirus is designed to induce the immune system to generate a protective response against SARS-2. The platform has not been used in an approved vaccine, but has been tested in experimental vaccines against other viruses, including the Ebola virus.”

The American Phase 3 trial seeks 30,000 participants, according to a press release.

In the statement from AstraZeneca, the company spokesperson noted that “in large trials, illnesses will happen by chance but must be independently reviewed to check this carefully.” The spokesperson also said the company is “committed to the safety of our participants and the highest standards of conduct in our trials.”

It was not immediately clear what steps were being taken at American sites in response to the hold. Usually, clinical holds involve a pause in finding new participants and dosing those already present until it is deemed safe to continue.



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