GENEVA — A top international Red Cross organization has announced a 100-million Swiss franc ($110 million) plan to help support the immunization of 500 million people worldwide against COVID-19 amid concerns about vast inequalities in the rollout of coronavirus vaccines between rich and poor countries.

The International Federation of Red Cross and Red Crescent Societies, an umbrella organization of national groups, says the world’s 50 poorest countries have received only 0.1% of the total vaccine doses that have been administered worldwide so far — with 70% administered in the 50 richest countries.

The federation on Thursday warned such inequality “could potentially backfire to deadly and devastating effect” because areas of the globe that remain unvaccinated could allow the virus to spread and mutate.

The plan involves rolling out national vaccination campaigns, steps to build trust in vaccines and efforts to “counteract misinformation about their efficacy,” it added. The initiative is to begin with 66 national Red Cross and Red Crescent Societies, and others are in talks with their respective governments.