The company behind a COVID-19 vaccine touted as a key tool for the developing world will miss a target for giving doses to the U.N.-backed effort to deliver shots to poorer countries.

COVAX planned to make available 250 million doses from Novavax by March.

But the U.N. agency in charge of deliveries says the first shipments likely won’t be made until April or May. Novavax had received $388 million from CEPI to not only fast-track the vaccine’s development but also make the shot available in lower-income countries.

Still, tens of millions of doses of the vaccine have already gone to rich countries including Australia and the Netherlands.

The delay is the latest setback for COVAX, which has been repeatedly hit by supply problems and has missed numerous targets to share doses.

Vaccine supply is improving lower-income regions, but experts say logistical problems continue.

According to data from Oxford University, only about 14% of people in low-income countries have received one vaccine dose.