Most of them are factory workers, public employees and civil defense force personnel.
Nguyen Hoang Chuong, who lives in Hoc Mon District, said: "Wearing a mask, still I feel insecure because it's too crowded. But if I leave now, I'm afraid I won't have the opportunity to get the jab again, because it is my workplace that has enlisted me for the vaccination.
"There should be careful and specific guidance for getting in line out here."
Inside the stadium, 46 tables are operated by 230 medics from nine different hospitals and clinics in town monitoring health conditions prior to and after vaccination, along with administering the shot.
It is expected the Phu Tho Stadium station would be run for three days starting Thursday.
A factory worker with a face shield is injected with the AstraZeneca vaccine.
The vaccination program at Phu Tho Stadium is part of a major inoculation campaign against Covid-19, the biggest in the city and nation's history, in which up to 836,000 doses of the AstraZeneca vaccine are scheduled to be administered within seven days. These are part of the 966,320 doses provided by Japan last week.