The conventional wisdom on MERS is that... if you're healthy, you will only suffer a mild illness if you contract the virus.
But things appear to be taking a turn.
Four MERS patients who didn't have any existing ailments have died, while two patients in their 30s are in critical condition.
Han Da-eun has more.
A 61-year-old man who contracted the MERS virus while visiting his sick cousin at Samsung Medical Center... and then passed away on June 14th from pneumonia.
A 72-year-old woman who was hospitalized at Pyeongtaek Saint Mary's Hospital... and died on the 12th due to lung failure.
Neither patient had a pre-existing illness.
Patients 98 and 123, who died overnight on Monday, were also free of any existing ailments.
These four cases are ringing alarm bells with medical experts,... as they go against the conventional wisdom about MERS that it is not a threat to people who are healthy.
The virus' incubation period of two to 14 days also seems to be breaking rules in Korea.
Patient 146 contracted the virus from Patient 14, known as a "super spreader," between May 27th and 29th,... but it was 16 to 18 days before he started showing symptoms of MERS.
And Patient 149 tested positive for the virus about 20 days after first coming into contact with someone with MERS.
As the virus is relatively new, not only to Korea but to the world,... Korean health officials are having a hard time trying to get a handle on cases like these.


"The incubation period is known to be from two to 14 days, but it can vary according to how you define the 'first contact' or 'initial symptoms.'"

Currently, patients in their 50s represent the biggest proportion of MERS cases, followed by those in their 60s and those in their 40s.
But the number of patients in their 40s is on the rise.
On top of an increasing number of tertiary infections,... cases like these that challenge the conventional wisdom on MERS are making it harder for Korea's health authorities to get a full picture of the disease