Worry about the disease has been reflected across the region with dozens of suspected cases being tested in Hong Kong, though none confirmed, and many thousands of people cancelling trips to South Korea.
The outbreak, with 122 cases and 10 deaths, is the largest outside Saudi Arabia and began last month when a 68-year-old South Korean businessman brought the disease back from a trip to the Middle East.
He was diagnosed with MERS on May 20, and all subsequent infections have been traced to him and happened in health facilities.
The 10th person to die was a 65-year-old terminal lung cancer patient whose condition deteriorated after testing positive for the MERS virus, South Korea's health ministry said.
President Park Geun-hye has put off a trip to the United States to deal with the outbreak as the total number of cases rises daily.
The central bank of Asia's fourth biggest economy said it had to act and cut its policy rate by 25 basis points to a record-low 1.50 percent.
"We decided to cut rates today in a pre-emptive move to contain the economic fallout from MERS," Bank of Korea Governor Lee Ju-yeol told a media briefing.
Policymakers were already under pressure to stimulate the economy as weak global demand and a strong won have dented exports and discouraged spending by consumers and companies.
One positive sign was a decline in the number of South Korea's schools and universities that have closed.
The total dipped to 2,622 on Thursday from about 2,700 the previous day after a joint team of experts from the World Health Organization (WHO) and South Korea recommended that schools be reopened as they were unlikely to spread the disease.
Some schools were set to reopen on Monday as the province of Gyeonggi, which surrounds the capital, said it would call off an advisory to suspend classes.
"We all need to put behind us excessive fear and psychological withdrawal over MERS and try to go back to normal daily lives next week so we can minimise the impact on the economy," Kim Moo-sung, who heads the ruling Saenuri party, said at a party meeting.
Hong Kong alert
MERS was first identified in humans in 2012. Most of the global cases, which number 1,271 according to WHO data and at least 448 related deaths, have been in the Middle East.
But memories are fresh in Asia of Severe Acute Respiratory Syndrome (SARS), which emerged in 2002-2003 and killed about 800 people worldwide.
MERS is caused by a coronavirus from the same family as the one that caused SARS. It is more deadly than SARS but does not spread as easily, at least for now.
Its symptoms include fever and a cough.
In Hong Kong, a clinic said it was testing two people who had both recently travelled to South Korea. Thirty-one people in Hong Kong who suspected they might have caught the disease have tested negative.
Hong Kong issued a "red alert" advisory on Tuesday against non-essential travel to South Korea, while Singapore Airlines said it would waive fees for customers who want to cancel or re-book flights to South Korea.
Despite the fears, only one case has been reported outside South Korea in the current outbreak, that of a South Korean man who travelled to China via Hong Kong after defying a suggestion from health authorities that he stay in voluntary quarantine at home.
China's Center for Disease Control and Prevention said the country was fully capable of containing any outbreak.
"There is no need to panic," the Xinhua news agency quoted the centre's deputy head, Feng Zijian, as saying.
Among the new South Korean cases was a pregnant woman who contracted the virus in an emergency ward that has been linked to other confirmed cases, the health ministry said.
The woman's pregnancy would limit the scope of treatment available, but she was in stable condition, the ministry said. The woman's parents had previously tested positive for MERS.
Another new patient was a police officer in the city of Pyeongtaek, where dozens of infections occurred, all linked to the first patient.
Three more patients were discharged, the health ministry said on Thursday, taking the total number of patients recovered in the outbreak to seven. — Reuters
