In Europe, regulators are reviewing the Johnson & Johnson vaccine for unusual blood clots.

Regulators follow up on a few reports of unusual blood clots

European regulators are reviewing Johnson & Johnson’s COVID-19 vaccine for unusual blood clots similar to the possible risk from another vaccine, the one made by Astrazeneca.

Earlier this week, the European Medicines Agency cited a possible link between the Astrazeneca vaccine and a rare clotting disorder. The J&J vaccine is made with a similar technology, prompting questions about the possibility of similar side effects.

The European group said Friday that it is investigating four reports of unusual clots, one in a J&J study and the others during the U.S. rollout of the one-dose vaccine.

Before clearing the J&J shot for U.S. use, the Food and Drug Administration investigated the clot that occurred during testing. At the time, the FDA said it would monitor for any red flags as the vaccine was used more widely.

Earlier this week, the European regulators said there have been three additional U.S. reports of clots with “some similarities,” out of almost 5 million vaccine recipients.

The EMA on Friday reiterated that it’s not clear if the small number of J&J reports are linked to the vaccine, which is expected to roll out in Europe in a few weeks.

In a statement Friday, J&J said

“no clear causal relationship has been established between these rare events” and the vaccine, but that it continued to work closely with regulators to assess the data.

In other developments:

■ In its weekly epidemiological update, the World Health Organization said more than 4 million COVID-19 cases were reported in the past week. New deaths increased by 11 percent from last week, with more than 71,000 reported.

■ French President Emmanuel

Macron acknowledged the U.S. “won the bet” on coronavirus vaccines by investing massively and moving fast with experimental treatments. He urged his compatriots to join a “national war effort” to administer and make vaccines. Macron visited a French factory Friday that started bottling and packaging Pfizer vaccines this week.

■ Greece’s national vaccination committee on Friday announced it is recommending the Astrazeneca vaccine continue to be administered to people 30 and older.

■ Many private-practice doctors, dentists and health care workers in Mexico are protesting that they have not been prioritized in the government-run coronavirus vaccine program even though they are exposed to possible infection at work. President Andrés Manuel López Obrador defended the vaccination program on Friday, saying it had to focus on people over 60 years old to prevent deaths.