The US government has only contracted for enough doses of AstraZeneca's Evusheld to cover less than one-tenth the number of people who are eligible for it, reported CNN. The FDA authorised the COVID-19 antibody treatment for immune-compromised earlier this month.

The first batch of Evusheld shipped out on December 20, according to a spokesperson for the US Department of Health and Human Services.

Camille Kotton, an infectious disease expert at Mass General Brigham, said her medical system expects to receive in this shipment only doses to treat fewer than 1% of its thousands of immune-compromised patients.

"It's a shame that something that really could be a game changer for people who didn't have a good vaccine response is now going to be something that is in short supply," said Dorry Segev, a leading researcher on vaccine effectiveness for people who are immune-compromised.

In a clinical trial with more than 5000 participants, those who received Evusheld saw a 77% reduced risk of developing COVID-19 compared to those who received a placebo, according to the FDA.

Four percent of the people in the trial were immune-compromised, according to a company spokesperson, but their results have not been published separately.