The European Medicines Agency ( EMA ) acknowledged on Tuesday that blood clots should be considered "very rare" side effects of Johnson & Johnson's covid-19 vaccine , whose benefits continue to outweigh the risks.

The EMA's decision comes just days before US health authorities rule on the Johnson & Johnson immunizer, at a time when vaccination is spreading to the entire US population.

The Amsterdam-based EMA recognized "a possible link" between the vaccine from this US laboratory and registered cases of blood clots, which should be included as "very rare side effects" of the drug.

The European regulatory body concluded "that a warning about unusual blood clots with low blood platelets would have to be added to the product information."

It is an important decision, since several European countries count on this vaccine to accelerate their immunization campaign.

In the United States, the Johnson & Johnson vaccine should receive a new authorization, perhaps accompanied by "restrictions," according to White House medical adviser Anthony Fauci, who said an announcement will be made on Friday.

The US health authorities last week recommended "a pause" in the use of the drug of J&J after the appearance of serious cases of blood clots in several people.

That vaccine had a new setback in the United States, where regulatory authorities on Monday ordered the halt of production in a factory, where 15 million doses of the drug had previously been damaged.