People in the US have started receiving the one-dose Johnson& Johnson COVID-19 vaccine following an 11-day pause initiated after a rare blood clotting disorder was associated with the shot.

The Food and Drug Administration, or FDA, and the Centers for Disease Control and Prevention, or CDC, determined on Friday that the benefits of the one dose J&J vaccine outweigh the risks of keeping it off the market.

The announcement came after an external panel of scientific advisers said it believed J&J's one-dose vaccination should resume for everyone aged over 18, although with an FDA warning.

"The state of New York will resume administration of this vaccine at all of our state-run sites effective immediately," Governor Andrew Cuomo said on Saturday.

Since J&J had distributed millions of doses before the recommended pause, vaccination sites should have supplies readily available and could start resuming use of the vaccine immediately, health officials said. The final decision on whether to administer the vaccine will be taken by US states and healthcare providers.

Of nearly 8 million people who have received the vaccine, 15 people have developed blood clots and three have died. Four of the first six patients who developed clotting and low platelets after vaccination were treated with heparin, which can worsen their condition. Health authorities now say non-heparin blood thinners should be used.

The rate of the rare clot condition in J&J vaccine recipients was about 1.9 cases per million people overall, but 7 cases per million for women aged 18 to 49. In women over 50, the case rate was 0.9 per million.

New label

J&J said it had agreed to a new label with the FDA warning that "adverse events" had been reported after using the vaccine, mostly in women from 18 to 49 years old.

Everyone who receives the shot should receive an information sheet mentioning the rare clotting problem and symptoms to look for, officials said.

Regulators said the pause was necessary to evaluate the medical evidence and warn doctors about potential problems, especially for women aged under 50.

"Both agencies have full confidence that this vaccine's known and potential benefits outweigh its known and potential risks in individuals 18 years and older," said Janet Woodcock, the FDA's acting commissioner.

The European Medicines Agency this month found there was a "possible link" between the J&J vaccine and blood clots, but concluded the benefits outweighed the risks.