TEL AVIV (BLOOMBERG) - While countries around the world scramble for coronavirus vaccines, Israel has so many shots that it's keeping its Moderna Inc supply on hold.

And it's doing so while under fire for not inoculating the millions of Palestinians under its control.

Vaccine supply has outstripped demand in the world's leading inoculator per capita, which has contracted to receive millions of doses from Pfizer Inc and BioNTech SE in exchange for extensive data on the country's vaccine roll-out.

People under 50 have been less eager than their older compatriots to line up for a shot, so the pace of vaccination has slowed, with 40 per cent of the country's 9.3 million people having received a first inoculation.

Thanks to steady Pfizer shipments, much of the only delivery from Moderna, totalling around 100,000 doses, remains in cold storage, according to Mr Eli Gilad, a senior Health Ministry official working on the coronavirus.

"The amount of Moderna in Israel is very small" and it isn't worth putting another vaccine into circulation when the country is using millions of Pfizer doses, Mr Gilad said.

The Moderna supply - which was delivered in January and can remain in longer-term storage for six months - will eventually be used and there hasn't been any change to expected shipments, Mr Gilad said.

Guidelines for the vaccine's use haven't been issued, said Mr Avi Levin, who manages the Tel Aviv vaccine complex for Israel's largest healthcare provider, Clalit Health Services.

Israel is also postponing receipt of the supply it's allotted through a World Health Organisation-backed program, an Israeli official said on condition of anonymity to discuss vaccine strategy.

Two thousand Moderna doses were transferred to the West Bank-based Palestinian Authority to inoculate medical workers, with an additional 3,000 planned.

But for the most part, Israel is brushing off calls to provide vaccines for Palestinians.

Some officials and advocacy groups say Israel has a responsibility or interest in inoculating the millions of Palestinians under its control.

"The argument that you cannot afford to give the Palestinians doesn't hold anymore," said Dr Zvi Bentwich, a board member of Physicians for Human Rights - Israel.

The unused Moderna doses, he said, "reinforce that argument".

But even a programme to vaccinate Palestinians who work in Israel isn't in the offing yet, according to Israel Deputy Health Minister Yoav Kisch.

While Moderna and Pfizer both use similar technology and demonstrated near-identical results, there are small differences.

The interval between Pfizer shots is three weeks compared to four for Moderna, and Moderna's vaccine is easier to store and transport, while Pfizer's requires ultra-cold temperatures.

The minor discrepancies shouldn't deter Israel from using Moderna, said Dr Eli Waxman, a physicist leading a team advising Israel's national security council.

"The most important thing is to get as many vaccines as we can - Moderna, Pfizer - and get people vaccinated," Dr Waxman said.

"I believe that they would be able to handle such a modification without great difficulty."