3 more deaths over the deadly Middle Eastern Respiratory Syndrome (MERS) has been recorded in South Korea.

However health authorities said they were cautiously optimistic the worst was over as the number of new cases was falling.

According to Kwon Jun-Wook, a senior health ministry official, the plasma therapy is still under clinical testing but is now being used on two MERS patients at two different hospitals.

He further added that the health ministry has approved the experimental therapy on the advice of doctors and experts

In the meantime, 4 new cases were also confirmed today (Tuesday), bringing the total number of cases to 154, including 19 deaths.

Over 5,500 people are in quarantine while some 3,500 others have been released.

Reports say most of those who have died had pre-existing health problems.

According to the health ministry, of the 135 non-fatal cases, 17 have recovered and been released from hospital, while 16 of the 118 MERS cases still being treated are reported as being unstable.

The number of new cases has however been gradually declining from 12 on Friday to 4 on Tuesday, sparking hope the outbreak might be showing signs of easing.

Meanwhile, Jun-Wook said the health ministry has approved the experimental therapy on the advice of doctors and experts.