The latest National Disaster Management Office report said a more detailed picture of damage from Tropical Cyclone Hola was emerging.
Information from aerial assessments and on-ground reports showed central, northeast and northwest Malekula and north Ambrym were the most affected areas.
Underground water catchments and water supply systems were unsafe, some homes had been damaged, crops of bananas, taro, manioc, and other fruit trees had been destroyed.
Flooding and fallen trees had blocked roads, telecommunication remained patchy and the MV Rosali was shipwrecked in Malekula.
The NDMO warned there was a risk for outbreaks of diarrhoea, malaria and dengue fever.
Similar problems of damaged homes and gardens as well as unsafe water exist on south Pentecost and some crops were lost on West Malo.
On the volcanic island of Ambae Hola has caused acid rain and heavy ashfall of up to 5mm over the southern part of the island.
There has been no information received by the disaster office from Aneityum, due to break-down in communications.