AstraZeneca Pause Temporary the Vaccine of SARS-CoV-2, (AZD1222) and Resumption of the Third Phase Trials

Ali Dawood^*
*Correspondence: Ali Dawood, College of medicine, University of Mosul, Iraq, Tel: 9647701768002, Email:

Letter to Editor

AstraZeneca announced it was halting a late-stage trial of a major candidate vaccine for COVID-19. The study was suspended due to the exposure of one of the study participants to an unexplained disease. The company explained after the standard review process that the vaccination was paused to allow review of safety data by an independent panel. The event has been described as a suspected serious adverse reaction which means that the evidence indicates that the disease is related to the vaccine. The company subsequently resumed clinical trials of the vaccine.

A study was testing a vaccine being developed by collaboration between AstraZeneca and researchers from the University of Oxford. The vaccination paused due to the exposition of illness of one of the participants reported in the United Kingdom. The company did not disclose further information about the case and when it happened but the participant is expected to recover soon. The event was described as a suspected serious adverse reaction which means evidence suggests the illness is related to the vaccine.

The company stated that the illnesses will happen by chance during large trials but these illnesses must be independently reviewed to check and evaluate. The suspension of the trial has impacted other vaccine trials from the other vaccine makers. Currently conducting clinical trials are also looking for signs of similar adverse reactions shares of AstraZeneca fell more than 8% while shares of competitor vaccine developers rose ModernaInc was up more than 4% and Pfizer Inc rose less than 1%. A phase study 1 and 2 of the AstraZeneca vaccine reported that about 60% of 1000 participants’ sophisticated side effects of the vaccine.

The new vaccine AZD1222 uses a strain of adenovirus that carries a gene for one of the proteins in SAS-CoV-2. The adenovirus is designed to induce the immune system to generate a protective response against SAS-CoV-2. Nine of vaccine developers in the US and European pledged to commit to scientific safety standards for their experimental vaccines. Despite the urgency to contain the pandemic, the companies including AstraZeneca, Pfizer, and Moderna issued a "historic pledge" after a rise in concern that safety standards might not be well maintained. Biotechs are facing political pressure to release a vaccine as soon as possible.

Trials of the third stage of the (AZD1222) vaccine have resumed on 12th September 2020 in the UK after being halted earlier, although researchers predict that some participants may become ailing so each case should be evaluated for safety assessment.