AstraZeneca's COVID-19 vaccine trials still on hold in US over safety concerns

AstraZeneca's COVID-19 vaccine trails remain on hold in the United States, despite resuming in countries such as the United Kingdom, India, Brazil, and South Africa. On September 19, the New York Times reported on the recently published document by AstraZeneca describing protocols of how the trials are being conducted by the pharmaceutical company. The blueprint came amid increasing pressure from the scientific community who demanded AstraZeneca to be more transparent about its vaccine trials. 

Read: US FDA Investigating AstraZeneca's COVID-19 Vaccine Trial, Says Chief

As per the report, the United States Food and Drug Administration (FDA), which is the top-most authority that clears or holds vaccines, did not allow AstraZeneca to resume trials. The National Institutes of Health, an agency of the US Health Department said that it is a "standard procedure" to pause the trials as they are not sure whether the illness in volunteers was coincidental or tied to the vaccine. In the study published on Saturday, AstraZeneca, however, did not reveal many details about the illness in volunteers

Read: COVID-19 Vaccine: AstraZeneca CEO Says 2020 Approval 'on Cards' Despite Trial Pause

This comes after the company paused the trials earlier this month as two of the volunteers developed illnesses. Clinical trials of the vaccine, AZD1222, resumed in the UK following confirmation by the Medicines Health Regulatory Authority (MHRA) that it was safe to do so. On September 12, AstraZeneca had said that it cannot disclose further medical information on the trials. 

Read: WHO Says Safety 'first & Foremost' After AstraZeneca Suspends Vaccine Trials

AstraZeneca's COVID-19 vaccine

AZD1222, which was being dubbed as the front-runner in the vaccine race by WHO, has been developed by the University of Oxford in partnership with AstraZeneca. 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 COVID-19 virus if it later infects the body, said the company.

Read: AstraZeneca Puts Its COVID-19 Vaccine Trial On Hold After Patient In UK Falls Ill