US health authorities are calling for a pause in the use of the Johnson & Johnson COVID-19 vaccine, after reports of extremely rare blood clotting cases, this is according to BBC News Service.

News reports show that the Food and Drug Administration (FDA) said it was acting 'out of an abundance of caution', because six cases of severe blood clotting had been detected in more than 6.8 million doses of the vaccine.
The recommendation follows similar rare cases in the AstraZeneca vaccine, which have prompted some curbs in its use.
BBC says the both FDA and the Centers for Disease Control and Prevention (CDC) were reviewing six reported US cases of a rare & severe type of blood clot in individuals after receiving the vaccine, but right now, these adverse events appear to be extremely rare.
“We are recommending a pause in the use of this vaccine out of an abundance of caution,” the FDA said.
This is said to be a measure to ensure that the health care provider community is aware of the potential for these adverse events.
A joint statement from the FDA and CDC clarified that the blood clotting was cerebral venous sinus thrombosis (CVST) which is said to need a different treatment than a usual one, adding that a common treatment - an anticoagulant drug called heparin 'may be dangerous', and an alternative is required.