Super-spreading events of MERS-CoV infection
Authors: David S Hui
Journal: The Lancet (2016)

Middle East respiratory syndrome coronavirus (MERS-CoV) was first identified in September, 2012, from a 68-year-old man who had died of severe pneumonia and multiorgan failure in Saudi Arabia in June, 2012.1Zaki AM van Boheemen S Bestebroer TM et al.Isolation of a novel coronavirus from a man with pneumonia in Saudi Arabia.N Engl J Med. 2012; 367: 1814-1820Crossref PubMed Scopus (4187) Google Scholar Since then, MERS-CoV infection has spread to 27 countries, including South Korea, where 186 cases had been confirmed within 2 months following the return of a Korean businessman (Patient 1) who had visited four countries in the Middle East between April 18 and May 3, 2015.2WHOMiddle East respiratory syndrome coronavirus (MERS-CoV)—Republic of Korea. Disease outbreak news 24 May 2015.http://www.who.int/csr/don/24-may-2015-mers-korea/enGoogle Scholar This major outbreak in South Korea is characterised by five super-spreading events in hospital settings,3Korea Centers for Disease Control and PreventionMiddle East respiratory syndrome coronavirus outbreak in the Republic of Korea, 2015.Osong Public Health Res Perspect. 2015; 6: 269-278Summary Full Text Full Text PDF PubMed Scopus (202) Google Scholar of which two were related—one at Pyeongtaek St Mary's Hospital (Pyeongtaek; by Patient 1)4Kim KM Ki M Cho SI et al.Epidemiologic features of the first MERS outbreak in Korea: focus on Pyeongtaek St. Mary's Hospital.Epidemiol Health. 2015; 37: e2015041Crossref PubMed Google Scholar and one at Samsung Medical Center (Seoul; by Patient 14).3Korea Centers for Disease Control and PreventionMiddle East respiratory syndrome coronavirus outbreak in the Republic of Korea, 2015.Osong Public Health Res Perspect. 2015; 6: 269-278Summary Full Text Full Text PDF PubMed Scopus (202) Google Scholar During Patient 1's stay at Pyeongtaek St Mary's Hospital on May 15–17, 2015, he had infected 36 patients, including Patient 14, who was staying on the same floor.4Kim KM Ki M Cho SI et al.Epidemiologic features of the first MERS outbreak in Korea: focus on Pyeongtaek St. Mary's Hospital.Epidemiol Health. 2015; 37: e2015041Crossref PubMed Google Scholar Both Patient 1 and Patient 14 had sought medical attention at different health-care facilities before being treated at the Samsung Medical Center on May 17–20 (Patient 1) and May 27–29 (Patient 14), around day 7 of their illness when they were highly infectious. However, it was Patient 14 who had led to the major nosocomial outbreak at the Samsung Medical Center.3Korea Centers for Disease Control and PreventionMiddle East respiratory syndrome coronavirus outbreak in the Republic of Korea, 2015.Osong Public Health Res Perspect. 2015; 6: 269-278Summary Full Text Full Text PDF PubMed Scopus (202) Google Scholar Patient 1 had initially presented to the emergency room on May 17, 2015, when the hospital was full; he was admitted and isolated immediately on May 18, 2015, after his travel history to the Middle East was ascertained by a medical officer, without causing any nosocomial outbreak.4Kim KM Ki M Cho SI et al.Epidemiologic features of the first MERS outbreak in Korea: focus on Pyeongtaek St. Mary's Hospital.Epidemiol Health. 2015; 37: e2015041Crossref PubMed Google Scholar In The Lancet, Sun Young Cho and colleagues5Cho SY Kang J-M Ha YE et al.MERS-CoV outbreak following a single patient exposure in an emergency room in South Korea: an epidemiological outbreak study.Lancet. 2016; (published online July 8.)http://dx.doi.org/10.1016/S0140-6736(16)30623-7Google Scholar report results from their comprehensive retrospective investigation of the MERS-CoV super-spreading event at the Samsung Medical Center emergency room, including a review of closed-circuit security video footage and electronic medical records. This nosocomial outbreak was most intriguing, with 82 people (33 patients, eight health-care workers, and 41 visitors) being infected following exposure to Patient 14 on May 27–29 in the emergency room. Patients staying in the same zone as Patient 14 had the highest attack rate (20% [23 of 117 patients]), compared with 5% (three of 58) in those with brief exposure to Patient 14 at the registration area or the radiology suite of the emergency room, and 1% (four of 500) in other patients who stayed in different zones. The median incubation period of patients who stayed in the same zone as Patient 14 was shorter than that in patients who stayed in different zones (5 days [IQR 4–8] vs 11 days [6–12]; p<0·0001). No cases were documented in patients and visitors who had visited the emergency room on May 29 and were exposed only to potentially contaminated environment without direct contact with Patient 14.5Cho SY Kang J-M Ha YE et al.MERS-CoV outbreak following a single patient exposure in an emergency room in South Korea: an epidemiological outbreak study.Lancet. 2016; (published online July 8.)http://dx.doi.org/10.1016/S0140-6736(16)30623-7Google Scholar The data suggest that the location (and hence the timing) of exposure to Patient 14 was an important factor in determining the attack rate and incubation period. Several other predisposing factors to this super-spreading event included failure to implement strict isolation of patients and quarantine of contacts at the first outbreak hospital (Pyeongtaek St Mary's Hospital),3Korea Centers for Disease Control and PreventionMiddle East respiratory syndrome coronavirus outbreak in the Republic of Korea, 2015.Osong Public Health Res Perspect. 2015; 6: 269-278Summary Full Text Full Text PDF PubMed Scopus (202) Google Scholar, 4Kim KM Ki M Cho SI et al.Epidemiologic features of the first MERS outbreak in Korea: focus on Pyeongtaek St. Mary's Hospital.Epidemiol Health. 2015; 37: e2015041Crossref PubMed Google Scholar poor communication and knowledge of patient movement between hospitals, overcrowding in the emergency room, inadequate ventilation with only three air changes per h, and limited availability of isolation rooms in the emergency room.5Cho SY Kang J-M Ha YE et al.MERS-CoV outbreak following a single patient exposure in an emergency room in South Korea: an epidemiological outbreak study.Lancet. 2016; (published online July 8.)http://dx.doi.org/10.1016/S0140-6736(16)30623-7Google Scholar At least six air changes per h in existing hospital facilities are needed to reduce room contamination in the management of acute respiratory infections, whereas 12 air changes per h are recommended for new or renovated facilities, especially when managing patients receiving mechanical ventilation and during aerosol-generating procedures.6WHOWHO Guidelines. Natural ventilation for infection control in health-care settings. World Health Organization, Geneva2009http://whqlibdoc.who.int/publications/2009/9789241547857_eng.pdfGoogle Scholar Failure in infection control and prevention in health-care facilities has resulted in large numbers of secondary cases of MERS-CoV infection involving health-care workers, existing patients, and visitors in Saudi Arabia7Assiri A McGeer A Perl TM et al.Hospital outbreak of Middle East respiratory syndrome coronavirus.N Engl J Med. 2013; 369: 407-416Crossref PubMed Scopus (947) Google Scholar, 8Oboho IK Tomczyk SM Al-Asmari AM et al.2014 MERS-CoV outbreak in Jeddah—a link to health care facilities.N Engl J Med. 2015; 372: 846-854Crossref PubMed Scopus (363) Google Scholar and several other countries in the past few years.5Cho SY Kang J-M Ha YE et al.MERS-CoV outbreak following a single patient exposure in an emergency room in South Korea: an epidemiological outbreak study.Lancet. 2016; (published online July 8.)http://dx.doi.org/10.1016/S0140-6736(16)30623-7Google Scholar, 9Hijawi B Abdallat M Sayaydeh A et al.Novel coronavirus infections in Jordan, April 2012: epidemiological findings from a retrospective investigation.East Mediterr Health J. 2013; 19: S12-S18PubMed Google Scholar, 10Hunter JC Nguyen D Aden B et al.Transmission of Middle East respiratory syndrome coronavirus infections in healthcare settings, Abu Dhabi.Emerg Infect Dis. 2016; 22: 647-656Crossref PubMed Scopus (112) Google Scholar Common risk factors include exposure to contaminated and overcrowded health-care facilities, poor compliance with appropriate personal protection equipment when assessing patients with febrile respiratory illness, application of potential aerosol-generating procedures (eg, resuscitation, continuous positive airway pressure, nebulised drugs), and lack of proper isolation room facilities.5Cho SY Kang J-M Ha YE et al.MERS-CoV outbreak following a single patient exposure in an emergency room in South Korea: an epidemiological outbreak study.Lancet. 2016; (published online July 8.)http://dx.doi.org/10.1016/S0140-6736(16)30623-7Google Scholar, 7Assiri A McGeer A Perl TM et al.Hospital outbreak of Middle East respiratory syndrome coronavirus.N Engl J Med. 2013; 369: 407-416Crossref PubMed Scopus (947) Google Scholar, 8Oboho IK Tomczyk SM Al-Asmari AM et al.2014 MERS-CoV outbreak in Jeddah—a link to health care facilities.N Engl J Med. 2015; 372: 846-854Crossref PubMed Scopus (363) Google Scholar, 9Hijawi B Abdallat M Sayaydeh A et al.Novel coronavirus infections in Jordan, April 2012: epidemiological findings from a retrospective investigation.East Mediterr Health J. 2013; 19: S12-S18PubMed Google Scholar, 10Hunter JC Nguyen D Aden B et al.Transmission of Middle East respiratory syndrome coronavirus infections in healthcare settings, Abu Dhabi.Emerg Infect Dis. 2016; 22: 647-656Crossref PubMed Scopus (112) Google Scholar The customs of patients seeking care at different health-care facilities (so-called doctor shopping), as in the cases of Patients 1 and 14, and having friends and family members to stay with patients as caregivers at already overcrowded health-care facilities are unique factors in South Korea.11WHOWHO recommends continuation of strong disease control measures to bring MERS-CoV outbreak in Republic of Korea to an end. News release.http://www.wpro.who.int/mediacentre/releases/2015/20150613/enDate: June 13, 2013Google Scholar Although no aerosol-generating procedures were performed (with the exception of Patient 14 receiving supplemental oxygen at 2–5 L per min during his stay at the emergency room),5Cho SY Kang J-M Ha YE et al.MERS-CoV outbreak following a single patient exposure in an emergency room in South Korea: an epidemiological outbreak study.Lancet. 2016; (published online July 8.)http://dx.doi.org/10.1016/S0140-6736(16)30623-7Google Scholar the role of such procedures, environmental contamination, and asymptomatic carriers in disease transmission would require further investigation in future major nosocomial outbreaks of MERS-CoV infection. Good compliance with appropriate personal protection equipment by health-care workers when managing patients with suspected and confirmed MERS-CoV infection, early diagnosis, prompt isolation of infected patients, and improvement of ventilation in health-care facilities are important measures to prevent nosocomial outbreaks.12Zumla A Hui DS Infection control and MERS-CoV in health-care workers.Lancet. 2014; 383: 1869-1871Summary Full Text Full Text PDF PubMed Scopus (60) Google Scholar I was a member of the joint WHO–Republic of Korea Urgent Mission for the investigation of the outbreak of the Middle East respiratory syndrome in South Korea. I declare no other competing interests. MERS-CoV outbreak following a single patient exposure in an emergency room in South Korea: an epidemiological outbreak studyOur results showed increased transmission potential of MERS-CoV from a single patient in an overcrowded emergency room and provide compelling evidence that health-care facilities worldwide need to be prepared for emerging infectious diseases. Full-Text PDF