Disruptions to immunization programs across South Asia due to the coronavirus pandemic are upending attempts to vaccinate millions of children against deadly diseases, UNICEF has warned.

The pandemic has interrupted vaccine supply chains and left families fearful of attending clinics, UNICEF said, creating another looming health crisis in a region where 4.5 million children were not fully immunized against diseases such as measles, diphtheria and polio.

"While the COVID-19 virus does not appear to make many children seriously ill, the health of hundreds of thousands of children could be impacted by this disruption of regular immunization services," said Jean Gough, director of UNICEF's South Asia office, in a statement. "This is a very serious threat."