Wealthy countries may start to hoard COVID-19 vaccines again, threatening global supplies as they seek to shore up stocks to fight the new Omicron variant of the virus, a senior World Health Organisation official says.

The warning by the WHO’s vaccine director, Kate O’Brien, comes as supplies to the COVAX dose-sharing program run by the WHO and vaccine charity GAVI have increased in the past few months due to donations from wealthy countries and after India eased limits on exports of vaccines.

New Delhi’s move has meant the Serum Institute of India has resumed shipments of the AstraZeneca vaccine it makes, mainly for COVAX.

Pre-COVID-19, Ghana’s health system was overburdened. The virus has made everything harder, and vaccine inequity has made it harder still. Doctor Maame Yaa Acheampong gives his perspective on the need for #vaccinequity: https://t.co/obbEZQIIdY pic.twitter.com/zq0wjFmSV6

— Gavi, the Vaccine Alliance (@gavi) December 8, 2021

“We have to make sure that it (higher shipments) continues,” Dr O’Brien said in a briefing on Thursday.

“As we head into whatever the Omicron situation is going to be, there is risk that the global supply is again going to revert to high-income countries hoarding vaccine” as they seek to protect their ability to vaccinate their citizens, she said later.

Earlier in the briefing, she said a major problem for COVAX has been wealthy countries donating COVID-19 vaccines with a relatively short shelf life, while noting that wastage rates were also high in some wealthy countries.

COVAX has shipped 610 million doses of vaccines to 144 countries or territories since February, the GAVI website shows.