Pfizer and its partner BioNTech have asked US and European regulators to approve a booster dose following a two-shot regimen of their Covid-19 vaccine, based on evidence of greater risk of infection six months after inoculation.

The US Food and Drug Administration is aiming to give the green light for the Pfizer shots by early September, Reuters quotes the New York Times as reporting.

The World Health Organisation has, meanwhile, called for a halt to Covid-19 vaccine boosters until at least the end of September to allow for the inoculation of at least 10 per cent of the population of every country.

The United States, Britain, Brazil, Finland, France, Germany, Sweden, Indonesia, Thailand, Cambodia, Israel, Russia Singapore, South Korea, Switzerland, European Union and Gulf states are debating the need for booster shots and some might approve it.