Seven people will be prosecuted for allegedly accepting payments in exchange for an earlier slot in the state's free Covid-19 vaccination programme.
Two of the suspects were brought to appear at a press conference following a crime reenactment attended by Public Health Minister Anutin Charnvirakul at Bang Sue Grand Station.
The pair, identified as Pakamon Hormsak and Wichayapong Theera-angkhananont, were arrested at their apartment in Bangkok's Din Daeng district yesterday morning.
They were then brought to Bang Sue Grand Station, which currently doubles as Bangkok's main Covid-19 inoculation centre, to show officials how they managed to access and alter vaccine recipients data in the centre's database.
The couple were hired by a mobile phone service provider to help staff at the centre collect personal information from senior citizens who came for walk-in jabs in late July.
The couple allegedly told police they saw this as an opportunity to make money.
According to police, Ms Pakamon said she would key in the names of relatives. However, when others found out, cash offers from members of the public -- who still had to register for a spot in the state's vaccination programme -- began rolling in.
She said she made between 3-4 million baht for her "service", which she spent paying off debts racked up during the Covid-19 pandemic.
Authorities began looking for a possible data breach after they observed an unusual surge of people turning up for vaccinations at the centre.
On July 28 alone, more than 2,000 people turned up at Gate 4 of the station, which Ms Pakamon and her alleged accomplices had designated as a meeting-up point.
Police then questioned some of those who turned up at the gate, who told police they had paid Ms Pakamon and her accomplices between 400-1,200 baht in order to get vaccinated on that day.
Sriluck Ubonnuea, deputy director of Bang Sue Grand Station, then filed a complaint with the police against the gang for obtaining profits from the vaccine.
While Ms Pakamon, Mr Wichayapong and four of their accomplices have been caught, one person remains at large.
The suspects have been charged with tampering with a computer system in a way that endangers national security and public health, and defrauding others.
At the press briefing, Mr Anutin reminded the public that jabs under the national vaccination programme are free of charge. "It is state-sponsored and is a right," he said.
According to the police, more than 200 witnesses have been questioned so far.
Mr Anutin said the seventh suspect, Bundit Rungsawang, has informed police she will turn herself in. The gang is believed to have raked in more than seven million baht in vaccination "booking fees".