A key US vaccine advisory committee has voted to stop recommending all adults get the Covid-19 vaccine, which has until now been officially approved for most Americans annually since the pandemic.

The Advisory Committee on Immunization Practices (Acip) also narrowly voted against advocating prescriptions for the Covid vaccine.

In two days of meetings, Acip changed its recommendations on the combined measles, mumps, rubella, varicella (MMRV) vaccine, and delayed plans for a vote on the hepatitis B vaccine.

Health Secretary Robert F. Kennedy Jr., a vaccine sceptic, fired all 17 members of the committee in June and handpicked their successors, sparking uproar in the medical community.

The panel spent Friday debating the Covid-19 vaccine, which has for the past several years been a routine recommendation, like the yearly flu jab.

Acip voted to abandon broad support for recommending the jab, including for high-risk populations like people aged over 65.

Instead, it decided they could make their own decision after talking with a medical professional.

In May, the federal government stopped recommending Covid-19 vaccines for healthy pregnant women and children.

In one exchange on Friday, Kennedy's ally Dr. Robert Malone argued there was no evidence that the Covid vaccine prevented serious infection, while Dr. Cody Meissner countered that data suggests the jab does protect against infection.

During the same meetings, the panel debated new recommendations for the MMRV vaccine and also delayed deciding on guidelines for hepatitis B vaccinations for newborns.

Critics have raised concerns about Kennedy's influence over public health policies, as he has been skeptical about many vaccines.