Prime Minister Pham Minh Chinh said the use of the money should to be transparent, efficient and economical.
The decision to buy the vaccines takes the total number of Pfizer vaccines Vietnam has ordered so far to 51 million doses.
The government established the national Covid-19 vaccine fund in May to raise contributions from various sources and ease the burden on its finances.
Besides buying vaccines it is also used to fund studies into them and their production.
The fund’s website said it has raised VND8.665 trillion (almost $380 million) as of Friday.
Vietnam aims to obtain 150 million doses of vaccines to immunize 70 percent of its 96-million population by April next year.
As of August it had received 33 million doses from various sources, including aid and commercial contracts signed by the ministry and businesses.
More than 33 million people have been vaccinated so far, with 6.18 million getting two shots.