News-Middle East: The World Health Organization has condemned the rush by wealthy countries to provide COVID vaccine booster shots, while millions around the world have yet to receive a single dose.

Speaking before US authorities announced that all vaccinated Americans would soon be eligible to receive additional doses, WHO experts insisted there was not enough scientific evidence that boosters were needed and said providing them while so many were still waiting to be immunized was immoral.

"We're planning to hand out extra life jackets to people who already have life jackets, while we're leaving other people to drown without a single life jacket," WHO's emergency director Mike Ryan told reporters from the UN agency's Geneva headquarters on Wednesday.

"The fundamental, ethical reality is we're handing out second life jackets while leaving millions and millions of people without anything to protect them."

WHO called earlier this month for a moratorium on COVID vaccine booster shots to help ease the drastic inequity in dose distribution between rich and poor nations.

But that has not stopped a number of countries from moving forward with plans to add a third jab, as they struggle to thwart the Delta variant.

US authorities warned Wednesday that COVID-19 vaccination efficacy was decreasing over time, and said they had authorized booster shots for all Americans from September 20 starting eight months after an individual has been fully vaccinated.

The officials said that while the vaccines remain "remarkably effective" in reducing the risk of severe disease, hospitalization and death from the effects of COVID, protection could diminish in the months ahead without boosted immunization.

Washington had already authorized an extra dose for people with weakened immune systems.