While South Korea have announced a "de facto end" to the outbreak, WHO will not confirm an end until 28 days have passed without any new infections being reported.
"It is the judgment of medical experts and the government that people can now feel safe," stated Prime Minister Hwang Kyo-ahn in a government meeting on Tuesday, following the removal of the last person from quarantine the previous day.
The outbreak has caused great alarm across the country, with schools closing, tourists canceling visits and its economy dramatically slowing down as a result of Middle East respiratory syndrome (MERS). To date, there have been 185 confirmed cases in the country, with 36 people dying from the virus.
While South Korea has announced a "de facto end" to the outbreak, the World Health Organization (WHO) will not confirm an end until 28 days have passed without any new infections being reported - the last reported infection in South Korea was on July 4th, 2015.
There are two main questions that have been raised following the outbreak: how did the virus manage to affect so many people in a country far away from the geographic region where the virus is most prevalent? And could a similar outbreak occur in other countries with sophisticated health care systems?
In this Spotlight, we make a brief attempt to tackle these two questions while also giving an overview of the virus first identified in Saudi Arabia in 2012.
The origins of the outbreak
MERS is a viral respiratory disease that belongs to a large family of viruses that cause illnesses ranging in severity, from the common cold to severe acute respiratory syndrome (SARS).
The virus shares common symptoms with these diseases, with typical cases characterized by coughing, fever, shortness of breath and pneumonia. In severe cases, patients can experience respiratory failure, organ failure and septic shock. People with weakened immune systems, older patients and individuals with chronic diseases appear to be more vulnerable to severe cases of MERS.
MERS is a zoonotic virus - a disease that is passed from animals to humans. The majority of cases have originated from the Middle East, and when cases have been reported outside of this area, they have tended to involve travelers who visited the region.
The MERS outbreak in South Korea began in May 2015 and has been traced to a single person who traveled to the Middle East, visiting four countries during his trip. He returned to South Korea on May 4th, developed symptoms on May 11th and was diagnosed with the virus on May 20th.
- Around 30% of people that develop MERS die from the virus
- There is currently no vaccine to prevent MERS
- Unlike some viruses, MERS does not seem to spread readily among communities.
In the days between first developing symptoms and receiving a diagnosis, the patient visited four separate health care facilities. Here, the practice of "doctor shopping" may have contributed to the spread of the virus.
Dr. Stanley Perlman, from the Departments of Microbiology and Pediatrics at the University of Iowa, believes that poor handling of this initial patient made the outbreak as bad as it was:
"When a MERS patient came to the US or Europe, they were isolated when there was a hint of something going on. In this case, the patient wandered around hospitals and family members weren't protected and that's the reason why it's gotten worse than other non-Arabian countries."
At the start of June, it was estimated that the patient had infected at least 22 other people, including fellow patients, relatives and health care workers.
A large number of the MERS cases in the outbreak have come from two of the hospitals that the initial patient visited: St Mary's in Pyeongtaek and the Samsung Medical Center, Seoul, from which more than 50 confirmed cases have been traced.
"We sincerely apologize with our heads bent to the people for causing great concern as Samsung Medical Center became the center (of) the spread of MERS," said Song Jae-hoon, the president of the hospital, in an apology issued for the facility's handling of the outbreak.
A number of theories have been offered to explain why the virus, recognized as one that does not spread particularly easily among communities, has managed to affect so many people. It may have been a novel strain of MERS or there may have been serious lapses in infection control measures at some of the hospitals. At present, the reason is unconfirmed.
With the number of reported cases beginning to increase, other symptoms began to develop on a national scale. Visits to supermarkets and public events such as baseball games fell, concerts have been postponed and, according to tourism authorities, more than 54,000 tourists canceled visits to the country.
As the largest ever outbreak of MERS outside of the Middle East took hold, what measures did South Korea implement in order to bring the virus under control?
How did South Korea control the MERS outbreak?
The Korean government instigated a tried and tested method to tackle the spread of the virus - a method with roots in the "resilience management" practiced by the governors of 14th century Venice to halt the spread of the plague.
Measures included tracing all the individuals who may have come into contact with people infected with the virus, isolating these individuals in quarantine and strengthening infection control measures.
MERS is a relatively new condition for which no cure or vaccine is known. Scientists are also uncertain precisely how the virus transmits between humans.
More than 16,000 people were isolated in quarantine, including the inhabitants of an entire village after a case of MERS was confirmed there. All individuals placed into quarantine conditions were regularly monitored - either in person by health care workers if isolated in hospitals or by mobile phone if isolated at home.
Stringent public infection control measures have been implemented, such as the wiping down of supermarket trolley handles before and after use and the disinfection of subway stations and trains.
Infection control guidelines were issued to the public, recommending that people avoid visiting crowded places and wear face masks when out in public. More than a thousand schools across the country were shut down due to concerns about the virus.
However, a panel comprised of international and local health experts set up to assess the outbreak expressed some concern about the effect that certain measures - particularly the school closures - could have on the morale of the nation.
Assistant director-general for health security at WHO Dr. Keiji Fukuda said that transmission of the virus in schools had not been a feature of the outbreak, while "on the other hand, the closure of schools creates levels of fear and concern not [based on] a real reflection of danger."
Dr. Fukuda also told Science Insider that the practice of wearing face masks did not make sense as the risk of catching MERS on the street is incredibly low. "But if it makes people feel safer, I don't see any harm," he added.
Some of these measures may be considered to be overly strict. Their implementation, however, may have been due to criticism that the government received during the early stages of the outbreak when many believed that not enough was being done to battle the virus.
"There are things that could have been done better," admitted Dr. Jong-Koo Lee, a public health expert at Seoul National University.
In any case, WHO reported earlier this week that these intensified public health measures were responsible for bringing the MERS virus under control. Authorities will continue to be vigilant, but as the Prime Minister said, they believe that the general public no longer have anything to fear.
Should the rest of the world heed this 'wake-up call'?
"This is the global challenge of modern times: an infection [...] can now appear anywhere in the world very quickly," warns Dr. Fukuda.
With WHO referring to the outbreak as a "wake-up call," should other countries be more wary of the potential for events to the repeated elsewhere?
"In our interconnected world, pathogens can travel rapidly, and outbreaks can occur in unexpected places," says Dr. Shin Young-soo, WHO's regional director for the Western Pacific.
Basic hygiene measures such as washing hands thoroughly help prevent the spread of respiratory infections.
However, Dr. Perlman personally believes that people in the US should not be worried about the disease - "but I can understand the fear factor," he adds.
The Centers for Disease Control and Prevention (CDC) state that MERS represents a very low risk to the general American public, with only two cases having ever been reported in the US - both in May 2014, involving recent visitors to Saudi Arabia and independent of each other. At the same time, more than 500 individuals have been tested for the virus with negative results.
Recently in the UK, the emergency department of a hospital was closed due to fears that patients with MERS were present. Earlier this week, it was announced that the two patients concerned both tested negative for the virus. No cases have been reported in the country since February 2013.
Experts believe that the MERS outbreak in South Korea is not exceptional in size, comparing it to previous outbreaks in Saudi Arabia where the virus was first discovered. In addition, it is believed that because the Korean authorities began to test so thoroughly for MERS, many mild cases that may have been missed in previous outbreaks have been recorded.
MERS does not spread well between people, and once infection control measures were pursued aggressively by the Korean authorities, the virus was well-controlled. The outbreak seems to have only occurred during a brief period where effective infection controls were not employed.
As long as authorities are aware of the risk such viruses pose and implement effective infection control methods as a standard care strategy, MERS should not pose a risk to countries with modern and sophisticated health care systems.
The CDC recommend that individuals contact a health care provider about MERS under the following circumstances:
- If they develop a fever or respiratory symptoms within 14 days of traveling from a country in or near the Arabian Peninsula
- If they have close contact with someone exhibiting these symptoms who has recently traveled from this area
- If they develop a fever or respiratory symptoms within 14 days of being in a health care facility in South Korea.
Outside of these circumstances, the risk of developing MERS is considered to be extremely low.