AstraZeneca’s Covid-19 Trial Paused After Adverse Reaction; Stock Falls 8%

Shares in AstraZeneca (AZN) plunged 8% in Tuesday’s after-hours trading after the biopharma put its late-stage Covid-19 vaccine trial on hold, due to a suspected serious adverse reaction in a participant in the UK, Stat News reports.

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“As part of the ongoing randomized, controlled global trials of the Oxford coronavirus vaccine, our standard review process triggered a pause to vaccination to allow review of safety data,” AZN said in a statement.

“This is 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 statement continued.

The University of Oxford/AstraZeneca vaccine candidate AZD1222 had already entered late-stage Phase III trials in the US, and is also undergoing trials in Latin America, Asia, Europe and Africa.

The vaccine uses a replication-deficient chimpanzee viral vector based on a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees and contains the genetic material of the SARS-CoV-2 virus spike protein. After vaccination, the surface spike protein is produced, priming the immune system to attack the SARS-CoV-2 virus if it later infects the body.

“In large trials, illnesses will happen by chance but must be independently reviewed to check this carefully. We are working to expedite the review of the single event to minimize any potential impact on the trial timeline. We are committed to the safety of our participants and the highest standards of conduct in our trials” AZN stated.

According to Stat News, an AZN spokesperson further elaborated that the pause is “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.” Another source said the trial was placed on hold out of “an abundance of caution.”

AZN shares have gained 10% this year as the drugmaker joined the list of companies engaged in the development of a potential coronavirus vaccine. Looking ahead, the $90 average analyst price target puts the upside potential at a promising 65% in the coming 12 months.

Overall, the stock scores a Moderate Buy consensus from the analyst community. (See AstraZeneca stock analysis on TipRanks)