The trials were paused after a volunteer became ill.

PITTSBURGH (KDKA) — Johnson & Johnson is halting its clinical trials for its experimental Coronavirus vaccine.

The company has hit pause because of an unexplained illness in one of its volunteers.

The drug company says that volunteer’s illness is being reviewed and evaluated.

Johnson & Johnson would not say what that illness is, but one point of clinical trials is to find out if vaccines cause dangerous side effects.

Experts from Brown University say a pause is not immediately concerning, adding it is expected and a reminder the vaccine takes time to create.

Last month, a Pittsburgh doctor discussed the safety measures that become standard practice once a vaccine is rolled out.

A UPMC doctor also said several weeks ago that a widely available vaccine before the end of the year was ‘not going to happen.’

This marks the second Phase 3 trial to hit the pause button in the United States.

AstraZeneca’s vaccine trial was paused last month after a volunteer experienced neurological complications in the United Kingdom.

That trial has resumed in other parts of the world, but it is still paused in the United States as the FDA investigates.

Johnson and Johnson started their Phase 3 trial in September.

It’s one of six vaccines being tested in the United States and one of four in the most advanced, Phase 3 stage — and the drug makers vaccine requires just one dose for patients.

Doctors say they want the vaccine to be safe and it’s going to take time.

They find it reassuring that companies are taking the trial responsibility and pressing pause when needed.