Countries across the world have ordered more than 800 million excess COVID-19 vaccines, with the option to buy another 1.4 billion doses, according to an estimate from the Global Alliance for Vaccines and Immunization (GAVI).

GAVI's CEO Seth Berkley, whose company forms one-third of the COVAX initiative, said he understood why countries bought more than they needed but urged them to donate any excess jabs to the fund to help support poorer countries.

The global COVAX initiative is coordinated between GAVI, the Coalition for Epidemic Preparedness Innovations (CEPI) and the World Health Organization (WHO) to ensure all countries have access to vaccines regardless of income levels.

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Countries were ordering COVID-19 vaccines before they were licensed by drugs regulators in a bid to speed up the vaccination process.

Addressing the virtual World Economic Forum, Berkley said countries "didn't know which vaccines were going to work, if any of them, so they took multiple shots at the goal, so to speak."

The UK, for instance, has agreed deals for 340 million doses of vaccine from six different producers, according to a paper from the British Medical Journal. That is more than five jabs for every person in its population, with many other countries following suit.

On Monday, the International Chamber of Commerce (ICC) published a study, saying that the global economy is set to lose $9.2 trillion if governments fail to ensure global access to COVID-19 vaccines.

The WHO has also urged wealthier countries not to take part in vaccine nationalism. "Until we end the pandemic everywhere, we won't end it anywhere," Director-General Tedros Adhanom Ghebreyesus said in press conference on Monday.

READ MORE: Vaccine nationalism could cost global economy $9.2 trillion

Berkley also gave countries several other options in case they were unable to donate them themselves.

"We are also in a position to buy them or to take a spot in a manufacturing queue to make them available equably," he added.

In order for them to be used properly, GAVI has said the vaccines must have a full shelf life, the ability to be used across the world and have come directly from manufacturers so they have been handled properly.