Asymptomatic infection of Middle East respiratory syndrome coronavirus using serologic survey in Korea

Song, Yeong-jun; Yang, Jeong-Sun; Cheong, Hae-Kwan; Yoon, Hee Jung; Nam, Hae-Sung; Lee, Soon Young; Park, WooJung; Park, SungHan; Choi, Bo Youl; Kim, Sung Soon; Ki, Moran

doi:2018.0.0.e2018014

Original article

Epidemiology and Health 2018;e2018014.
DOI: https://doi.org/10.4178/epih.e2018014 [Accepted] Published online April 15, 2018.

Asymptomatic infection of Middle East respiratory syndrome coronavirus using serologic survey in Korea

Yeong-jun Song¹

, Jeong-Sun Yang²

, Hae-Kwan Cheong³

, Hee Jung Yoon⁴, Hae-Sung Nam⁵

¹Department of Cancer Science and Population Health, National Cancer Center Graduate School of Cancer Science and Policy, Goyang, Republic of Korea
²Centers for Disease Control and Prevention, Cheongju, Republic of Korea
³Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
⁴The Korean Society of Infectious Diseases, Seoul, Republic of Korea
⁵Department of Preventive Medicine, Chungnam National University School of Medicine, Daejeon, Republic of Korea
⁶Department of Preventive Medicine, Ajou University School of Medicine, Suwon, Republic of Korea
⁷Department of Preventive Medicine, Hanyang University Medical College, Seoul, Republic of Korea

Correspondence Moran Ki ,Tel: +82-31-920-2736, Fax: +82-2-6008-6056, Email: moranki@ncc.re.kr

Submitted: March 26, 2018 Accepted after revision: April 15, 2018

Abstract

OBJECTIVES:
Asymptomatic infection rates of Middle East respiratory syndrome (MERS) coronavirus vary. To identify rates of asymptomatic MERS infection in healthcare workers and non-healthcare workers, serologic survey was conducted.
METHODS:
Study individuals were selected from the contacts based on a priority system in four MERS prone-regions. Sero-epidemiological analysis was performed in 1,610 contacts (average duration from exposure to test, 4.8 months), and the collected sera were tested using an enzyme-linked immunospecific assay (ELISA), immunofluorscence assay (IFA), and plaque reduction neutralization antibody test (PRNT). Of 1,610 contacts, there were seven ELISA-positive cases. Among these seven, one exhibited positive IFA and PRNT results.
RESULTS:
Asymptomatic infection rate was 0.06% (95% confidence interval, 0.0016-0.3461%). The asymptomatic MERS case was a hospitalized patient with the patient zero on the same floor of the hospital at the same time. The case was quarantined at home for 2 weeks after discharge. The case had underlying diseases, including hypertension, angina, and degenerative arthritis.
CONCLUSIONS:
The asymptomatic infection was acquired via healthcare-associated transmission. Thus, it is necessary to extend serological studies on inpatient contacts who have no symptoms.

Keywords: asymptomatic infection; epidemiology; Middle East respiratory syndrome coronavirus; nosocomial infections; outbreak; ELISA