Police in the north-central province of Quang Tri have pressed criminal charges against the deputy director and a nurse at a hospital for causing the accidental deaths of three newborns last year.
The local prosecution agency will consider ratifying the charges.
Lao Dong (Labor) newspaper reported that police placed Nguyen Van Thien, deputy director of Huong Hoa General Hospital in the namesake district and nurse Tran Thi Hai Van under criminal investigation on Sunday and put them under house arrest.
Police decided that the two were involved in the deaths of the babies on July 20 last year.
Specifics of the investigation and the extent of their involvement in the fatal tragedy are not available yet.
The victims were admitted to the hospital by their parents for Hepatitis B shots but were mistakenly given Esmeron, a muscle relaxant used prior to surgery or other procedures.
The newborns turned blue and had difficulty breathing 30 minutes after receiving the injections, police say.
They were rushed to the emergency room, but doctors failed to resuscitate them.
Nguyen Thi Thuan, the nurse who allegedly administered the shots, has been detained since early March.
Thuan had more than 20 years experience working as a nurse.
Media reports have quoted unnamed sources as saying that the hospital had suffered a power outage that day.
Thuan had used the light from her mobile phone to find the vaccine, only to select the muscle relaxation, they say.
Parents in Vietnam seek the first hepatitis B shot for their children within 24 hours of birth.
They then seek three subsequent shots when the baby is two, three and four months old.