The move followed the capital's decision Tuesday morning to ban gatherings of more than 10 people, except in offices, hospitals, schools and locations for election purposes, as well as shutting down food and beverage businesses, convenience stores and apartments for rent in areas around hospitals with coronavirus cases.
Vietnam will hold its general election for legislators of different levels on May 23.
The country is currently facing its toughest Covid-19 wave yet, which has seen 502 community cases in 26 cities and provinces since late last month. On Monday, 125 community cases were recorded in a single day, the highest daily infection tally observed ever since the disease appeared in Vietnam early last year.
Hanoi in particular has recorded 146 cases in total, with 93 reported in its now locked-down National Hospital for Tropical Diseases and K Hospital.
The capital has already suspended non-essential services like bars, dance clubs and karaoke parlors, as well as outdoor food stalls and cafes, to curb the spread of the disease.
The city has also advised people not to go out unnecessarily.