Heavy rain has triggered floods that have killed at least 65 people in northern and central Vietnam.
Authorities have warned of disease outbreaks, including cholera and dengue fever.
At least 18 people were killed in Hanoi in what is believed to be the heaviest flooding in the capital since 1984.
The Health Ministry alerted all clinics in flood-hit areas to be staffed around the clock to prepare for any outbreaks.
The Vietnamese government has also warned that more downpours, flash floods and landslides could be in store in mountainous provinces in the country's north-central region this week.
Up to 500mm of rain has fallen on Hanoi since Friday.
Landslides have eroded many sections of the north-south Ho Chi Minh highway in Thua Thien-Hue province.
Vietnam's main agricultural area, including the Central Highlands coffee belt and the Mekong Delta rice basket, have not been affected by the floods, although rain disrupted coffee harvesting last week.
In southwestern China, the death toll from mudslides caused by heavy rain has risen to 22 from 15, with 45 missing.
