The US Food and Drug Administration is expected to evaluate the efficacy of Moderna and Johnson & Johnson’s third dose of Covid vaccines this week.

The FDA’s Vaccines and Related Biological Products Advisory Committee will meet on Thursday and Friday, CNBC reported.

Earlier this month, the US regulators authorised Covid booster shots of Pfizer and BioNTech’s vaccine to a wide array of Americans, including the elderly, adults with underlying medical conditions and those who work or live in high-risk settings like health and grocery workers.

More than 7 million Americans have received a booster dose in the US as of Saturday, according to the latest data available from the CDC.

“Even with delta, the current vaccines are holding up quite well as far as hospitalisation and severe disease are concerned,” said Norman Baylor, former director of the FDA’s vaccines office.

The FDA advisory panel is scheduled to meet on Thursday to discuss data on the safety and effectiveness of a Moderna booster shot in adults. On Friday, the committee will debate J&J booster shots for adults, the report said.

The FDA’s final decision will be handed to the CDC and its vaccine advisory committee, which will then make their own decision.

The CDC’s next vaccine advisory meeting is scheduled for October 20-21 where it is expected to discuss the boosters.

Last month, Moderna said a third shot at half the dosage used for the first two jabs was safe and produced a stronger immune response than what was seen after the second dose in its phase three clinical trial, the report said.

J&J said last month a second dose of its single-shot vaccine was safe and boosted protection against symptomatic infection from around 70 per cent to 94 per cent when administered two months after the first dose in the United States, it added.

Meanwhile, experts from a World Health Organization (WHO) panel late on Monday recommended that Covid-19 booster shots should be offered to moderately and severely immunocompromised people, changing its stance on the third dose.

The WHO had earlier called for a global moratorium on Covid-19 booster doses, aiming for a more equitable distribution of vaccines globally to enable every country to vaccinate at least 40 per cent of its population.

Last week, the global health body announced an initiative to vaccinate 40 per cent of the population of every country against Covid-19 by the end of 2021, and 70 per cent by mid-2022.