AstraZeneca and Johnson & Johnson get FDA green light to resume coronavirus vaccine trials in the US after participants got sick

• Two major coronavirus vaccine trials — one by AstraZeneca and the University of Oxford, the other by Johnson & Johnson — will resume coronavirus vaccine trials in the US, the companies announced Friday
• AstraZeneca's late-stage trial had paused September 6 after the company reported "suspected serious adverse reaction" in a UK-based participant.
• Johnson & Johnson halted trials on October 12 after a participant developed an unexplained illness.
• The UK resumed clinical trials for AstraZeneca and the University of Oxford vaccines in September, and in Japan earlier this month.

Two major coronavirus vaccines will resume late-stage trials in the US

The Food and Drug Administration has allowed a COVID-19 a vaccine trial commissioned by AstraZeneca and the University of Oxford, as well as a trial by Johnson & Johnson, to resume within the US both companies announced Friday.

The AstraZeneca vaccine trial was halted on September 6 after the company reported "suspected serious adverse reaction" in a UK-based participant, STAT reported. The company said in a release that it's "not unusual" for participants to become sick in a large-scale vaccine trial.

Johnson & Johnson temporarily halted vaccine studies on October 12 after a participant experienced an unexplained illness. The Washington Post reported that a man who received the Johnson & Johnson drug suffered a stroke that may have been caused from infection.

The FDA plans to require AstraZeneca researchers to tell participants of the suspected adverse reaction, and monitor them for "neurological events," the Wall Street Journal reported.

Read more: The doctors and scientists who will evaluate every coronavirus vaccine met for the first time this week. Here are the 5 most important takeaways from their landmark meeting.

The UK resumed clinical trials for AstraZeneca and the University of Oxford vaccines in September, and in Japan, trials resumed earlier this month.

There are currently 193 research efforts to develop a vaccine, The World Health Organization has reported, and the head of the United States' vaccine effort recently told Business Insider's Andrew Dunn he expects Americans to receive shots in mid-2021.

Earlier this week, the FDA approved antiviral drug remdesivir to treat coronavirus patients after some studies found it helps hospitalized patients with more moderate forms of COVID-19 recover more quickly. It was the first coronavirus treatment to gain FDA approval. But even with the use of remdesivir, experts say vaccines are more important for stopping the spread of COVID-19.

The FDA did not immediately respond to Business Insider's requests for comment.