The United States can immediately resume use of Johnson & Johnson’s COVID-19 vaccine, top health regulators said on Friday, ending a 10-day pause to investigate the vaccine’s link to extremely rare but potentially deadly blood clots.

The Centers for Disease Control and Prevention (CDC) and Food and Drug Administration said in a joint statement that they would warn of the risk of a potentially fatal syndrome involving severe blood clots and low platelets in a fact sheet given to recipients.

Top US FDA officials said the decision was effective immediately, clearing the way for shots in arms as early as Saturday.

“We are no longer recommending a pause in the use of this vaccine,” CDC Director Rochelle Walensky told a news briefing.”Based on the in-depth analysis, there is likely an association but the risk is very low.”

The agencies made the decision following a meeting by outside advisers to the CDC who recommended that the vaccine pause be ended.

The agencies had been investigating the risks of the vaccine.

Earlier on Friday, the CDC panel voted 10-4 that the J&J vaccine be used as recommended in people 18 years of age and older, the parameters of its current FDA authorisation.

“The Committee’s recommendation is an essential step toward continuing urgently needed vaccinations in a safe way for millions of people in the US,” J&J’s Chief Scientific Officer Paul Stoffels said in a statement.

The CDC said that there had been 15 total cases of the syndrome, including the six original confirmed cases that all occurred in women. There were three deaths.

While the efficacy of the J&J vaccine in clinical testing lagged that demonstrated by the other two approved for use in the United States, it has the advantage over the ones produced by Pfizer Inc and Moderna Inc in that it is given with a single dose rather than two.

It also is stored in a refrigerator and does not need to be frozen during transport, which makes it better for hard-to-reach areas.

The US decision follows a similar one by the European Medicines Agency, which on Tuesday said the benefits of the J&J shot outweighed its risks and recommended adding a warning about unusual blood clots with low blood platelet counts to the vaccine’s product label. J&J resumed its roll-out there.

‘EXTRAORDINARILY RARE RISK’

“It is an extraordinarily rare risk. A number of vaccines have an extraordinarily rare risk,” said Dr. Paul Offit of the University of Pennsylvania, a member of the FDA’s vaccine advisory panel.

Dr. William Moss, executive director of the International Vaccine Access Center at the Johns Hopkins Bloomberg School of Public Health, said the vaccine should be used with warnings of the risk as it will help advance the vaccination effort.

“Giving people the choice to receive a single-dose vaccine will help get more people vaccinated faster and will better protect some populations, such as those who are homeless or incarcerated,” Moss said by email.

J&J has faced several setbacks since its vaccine gained US emergency authorisation in February, including drawing scrutiny over production shortfalls.

FDA inspectors this week cited along list of serious cleanliness and safety issues at an Emergent Bio Solutions plant making the J&J vaccine.

Johnson & Johnson shares closed up 0.2 %at $165.52.

The United States has made substantial progress in vaccinating its population in recent months compared to many other countries, with 35% of adults fully vaccinated and 53% having received at least one shot, according to CDC data. The United States leads the world with roughly 570 000 COVID-19 deaths.