COVID-19 vaccine makers AstraZeneca and Johnson & Johnson have announced that they will resume their paused coronavirus vaccine trials in the United States.

The said COVID-19 vaccine trials had been postponed due to health and safety concerns.

AstraZeneca's COVID-19 vaccine trial had been paused since early September. Johnson & Johnson's trial had been halted since early this month.

AstraZeneca said that the U.S. Food and Drug Administration had allowed the continuation of its trial on Thursday. After the FDA reviewed all the global safety data, it was concluded that it was safe to resume.

Its COVID-19 vaccine trials had already resumed in other countries. A volunteer in Britain has developed a neurological condition, which resulted in the postponement of AstraZeneca's trial. 

Johnson & Johnson's trial, on the other hand, was paused on Oct. 12 after a trial participant experienced an unexplained illness.

The company said Friday that "no clear cause" was determined for the trial participant's case.

"Preparations to resume the trial in the United States are now underway," the firm said in a CNN report.

Johnson & Johnson did not specifically say when it would start its trial. However, someone familiar with the process said it could start at some point next week.

"There are many possible factors that could have caused the event. Based on the information gathered to date and the input of independent experts, the company has found no evidence that the vaccine candidate caused the event," Johnson & Johnson said in a report.

The Johnson & Johnson vaccine trials started on Sept. 23. The company initially planned to test the vaccines on 60,000 patients in eight countries, including the U.S.

Johnson & Johnson said in its company statement that discussions with regulators around the world are progressing.

AstraZeneca Trials

AstraZeneca's COVID-19 trials have already resumed in the United Kingdom, Brazil, and South Africa. Its global trials were halted after an unexplained illness in a participant.

AstraZeneca is considered as one of the world's leading candidate and most advanced in terms of development. The trial's suspension upstarted a two percent fall in AstraZeneca's shares in London.

It also resulted in a 12 percent drop in its Indian unit's stock price, which is the AstraZeneca Pharma India Ltd.

Britain's Health Secretary Matt Hancock said the pause in developing their COVID-19 vaccine would not necessarily be a setback. He added that it depends on what they find when they do the investigation.

Reuters said that the nature of the participant's illness was not disclosed, but the participant is seen to recover.

Johnson & Johnson Trials

Johnson & Johnson also paused all of its clinical trials after a participant became sick with an "unexplained illness."

The company said adverse events, including illness and accidents, are expected in any clinical study, specifically large studies.

A day after Johnson & Johnson paused its trial, Eli Lilly also postponed its study, according to an NPR report.

The Eli Lilly trial is designed to test a monoclonal antibody in combination with remdesivir.

Remdesivir is an antiviral with emergency use authorization for the COVID-19.

President Donald Trump used the same compound treatment when he tested positive for COVID-19.

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