Five guards at the Corradino Correctional Facility have tested positive for COVID-19, a spokesperson for the Home Affairs Ministry confirmed on Monday.
They are recovering in isolation in their homes.
Prison guards worked on week-long shifts and stayed at the facility during the 'first wave' of the virus, but they have since returned to working their regular shift based on consultations with the health authorities.
The spokesperson said that 600 swab tests have been carried out on both prisoners and prison officials since COVID-19 was detected in Malta in March. Both inmates and staff are required to wear masks at all times.
Prison visits resumed in early June, but visitors can only speak to the inmates from behind perspex barriers while prisoners are also being encouraged to keep up with their relatives via Skype.
Earlier on Monday, two airline passengers arriving from Barcelona early in the morning tested positive for coronavirus at Malta International Airport.
In the last 24 hours, 55 people tested positive for the virus after 2,194 swabs were carried out.