Nguyen Van Dinh, Deputy Chairman of Vietnam Association of Realtors, said that the figure has risen from 300 closed floors in February due to the rising severity of the pandemic.
The remaining 200 floors are operating online with reduced scales as real estate demand slumps, he added.
Apartment sales in Ho Chi Minh City in the first quarter fell 50 percent year-on-year to 1,980 units due to coronavirus impacts, according to real estate market research firm Jones Lang LaSalle (JLL).
New supply fell to the lowest since 2014 at 2,256 units, it said, adding that most promotion events were suspended because of the disease.
Dinh said that due to dwindling revenue, real estate developers might delay their deadline to handover projects, pay debts to banks and pay salary to employees.
"As most of the capital for real estate projects are credit, businesses face bankruptcy should the disease persists."
The association has proposed that the government allows real estate businesses to delay their tax and land fees payment.