There were 122 prisons throughout the country with no Covid-19 infections on Tuesday, while the other 19 reported 1,087 new cases, Corrections Department director-general Ayut Sinthoppan said on Wednesday.
Mr Ayut also said he had been informed by the Disease Control Department that a consignment of 100,000 doses of vaccine was being allocated tor the Corrections Department.
These vaccines would be stored in hospitals aligned with the department.
They would first be distributed to the 122 prisons free of Covid cases. Vaccinations would probably begin on Thursday at prisons with zero infections in "red" areas, starting with the Samut Prakan Central Prison, he said.
Mr Ayut said preparations had also been made for the release of inmates who had completed their prison sentences.
Covid-free inmates would be tested for the virus before release. Those to be released from prisons in Bangkok and other high-risk areas would be ordered into quarantine after being discharged.
Their names would be sent to local health offices at least five days before their release.
Those suspected of being infected would be placed in 14-day quarantine for observation before being discharged.
If found to be infected, they would be transferred to local health offices for treatment, he said.