Health workers administering doses of vaccine for Covid-19 to inmates at Minburi Remand Prison in Bangkok, amid a surge in cases of the virus in overcrowded Thai prisons. Photo: AFP / Thailand's Ministry of Justice

Barefoot Thai prisoners rolled up their sleeves to get coronavirus jabs into tattooed arms Friday, as the kingdom seeks to tackle a mass infection outbreak in its overcrowded jails.

Authorities have been trying to contain a recent virus surge in the penal system, where some inmates have less space to sleep than the inside of a coffin.

There have been more than 35,000 positive cases inside prisons and inmates have been encouraged to wear masks even when they sleep at night.

The government has begun rolling out an initial batch of 300,000 Sinopharm doses across the kingdom’s jails.

Inmates at Chonburi Central Prison, two hours southwest of Bangkok, lined up Friday morning to receive their jabs.

“Overcrowding in prisons is a factor making it difficult to prevent this kind of disease,” said the institution’s director, Chan Vachiradath.

He said the nearly 6,300 inmates at his prison had so far remained coronavirus-free, but staff are on guard.

Every prisoner had to undergo a swab test before their vaccination and priority was given to elderly inmates and those suffering underlying medical conditions that made them more vulnerable to severe virus cases.

Thailand has about 311,000 prisoners, according to International Federation for Human Rights figures from earlier this year – more than two and a half times the system’s official capacity.

Four out of five prisoners are serving time for drug charges because of harsh anti-narcotics laws that can see offenders jailed for a decade for possessing just a few methamphetamine pills.