One-storey homes in parts of Thai Nguyen and Yen Bai provinces were almost completely submerged in the early hours of Tuesday, with residents waiting on the roofs for help.
As well as the dead and missing, flooding and landslides have also injured at least 752 people, officials at the ministry of agriculture said on Tuesday.
Before hitting Vietnam, Yagi left 24 people dead across southern China and the Philippines.
Meteorologists say that as the world warms, typhoons can bring higher wind speeds and more intense rainfall, although the influence of climate change on individual storms is complicated.
