The halt on the single-dose jab comes after six people in the United States developed a rare disorder involving blood clots within roughly two weeks of inoculation.
All six recipients were women between the ages of 18 and 48.
One woman died and a second woman in Nebraska has been hospitalised and is in critical condition, the New York Times reports.
“We are recommending a pause in the use of this vaccine out of an abundance of caution,” Dr. Peter Marks, director of the Food and Drug Administration’s Center for Biologics Evaluation and Research, and Dr. Anne Schuchat, principal deputy director of the C.D.C., said in a joint statement.
“Right now, these adverse events appear to be extremely rare.”
US federal distribution channels, including mass vaccination sites, will pause the use of the J&J vaccine, and states and other providers are expected to follow.
Scientists with The Food and Drug Administration (F.D.A) and the Centers for Disease Control (C.D.C) will examine possible ties between the vaccine and the disorder and determine whether the F.D.A. should continue to authorise use of the vaccine for all adults.
A total of 6.8 million doses of the Johnson & Johnson vaccine have been administered in the US, according to data from the Centers for Disease Control and Prevention.
"Right now, these adverse events appear to be extremely rare," the FDA said in a statement on Twitter.
"This is important to ensure that the health care provider community is aware of the potential for these adverse events and can plan due to the unique treatment required with this type of blood clot," it added.
It comes after the European Medicines Agency (EMA) said it is continuing to look at reports of rare blood clots related to the J&J jab.
The vaccine is yet to be approved for use in the UK, but the Government has ordered 30 million doses.
Prof Openshaw, a member of the Covid-19 clinical information network, told BBC Radio 4’s Today programme: “We still don’t know whether they are directly related and caused by the vaccine but it seems possible that they could be.
“We still have to bear in mind just how rare these events are, and we’re doing something at massive scale in terms of rolling out these vaccines, and there are many vaccines around.
“It wouldn’t be surprising to find the J & J, the Janssen vaccine, also causes rare blood clots, because it’s based on an adenovirus technology which is not that far away from the technology which is being used in the AstraZeneca vaccine.”