A panel of US experts has voted unanimously to recommend the Pfizer and Moderna Covid-19 vaccines over Johnson & Johnson's.

Nine people are known so far to have died: seven women and two men. A total of 16 million US residents have received the single-dose J&J vaccine.

The Advisory Committee on Immunization Practices (ACIP) recommended that the J&J vaccine be reserved for cases where patients are unable or unwilling to receive the more widely available Pfizer and Moderna jabs. The CDC must still decide whether to accept the panel's recommendation. The blood-clotting side effect remains rare, with federal health officials estimating that it has been reported at a rate of 3.8 per million doses given. Of the 57 confirmed cases, 36 were admitted to intensive care units. The dead ranged in ages from 28 to 62, with obesity the primary underlying medical condition.

All the cases so far have taken place within a month of the jab, the vast majority after nine days.

The use of the J&J vaccine was temporarily halted in April due to concerns over blood clots. The CDC has noted that the use of the vaccine prevented thousands of Covid-19-related hospitalisations, compared to a relatively small number of people who experienced the side effects.