The Department of Health said only 54 percent of people have got a third shot and 7 percent a fourth.
Some 79,000 doses of vaccines that have been handed over to the province are set to expire on Saturday and they have to be administered quickly so that they do not go to waste, authorities said.
Last week the province only recorded one or two infections a day.
The Ministry of Health has not made the third and fourth shots mandatory.
With the number of cases and deaths falling around the country, the pace of vaccination is slowing down in many places, leaving hundreds of thousands of vaccines lying unused.
Authorities in a district in the Mekong Delta's Soc Trang Province announced on Tuesday that people who had not received their fourth shot could not travel out of the district but reversed it the same day.