Asymptomatic Coronavirus Disease 2019 (COVID-19) Carriers: Are They Infectious?

Yen Shen Wong^1, , Dzawani Muhamad², Soon Hin How³, Mohamed Sapian Mohamed⁴, Nasrah Mohd Arif², Tze Vee Soh², Suzana Mohd Hashim⁴ and Norazmi Abdullah⁵

¹Department of Internal Medicine, Pekan Hospital, Pahang, Malaysia

²Infectious Disease Unit, Department of Internal Medicine, Tengku Ampuan Afzan Hospital, Pahang, Malaysia

³Respiratory Medicine Unit, Department of Internal Medicine, International Islamic University Malaysia, Pahang, Malaysia

⁴State Health Department of Pahang, Malaysia

⁵Hospital Director, Tengku Ampuan Afzan Hospital, Pahang, Malaysia

Cite this paper:
Yen Shen Wong, Dzawani Muhamad, Soon Hin How, Mohamed Sapian Mohamed, Nasrah Mohd Arif, Tze Vee Soh, Suzana Mohd Hashim and Norazmi Abdullah. Asymptomatic Coronavirus Disease 2019 (COVID-19) Carriers: Are They Infectious?. American Journal of Infectious Diseases and Microbiology. 2020; 8(3):113-117. doi: 10.12691/ajidm-8-3-4

Abstract

Coronavirus disease 2019 (COVID-19) is highly contagious in symptomatic patients as it is thought to be transmitted through respiratory droplets. However, it is debatable whether asymptomatic COVID-19 patients are contagious due to lack of data. From 1^st March to 15^th April 2020, a total of 247 COVID-19 cases were admitted to Tengku Ampuan Afzan Hospital and 1010 close contacts were identified. We studied the epidemiological and clinical outcomes in asymptomatic subjects, as well as estimated the metrics of disease transmission between asymptomatic, symptomatic, and pneumonia subjects. From a total of 125 asymptomatic subjects, majority (n=116, 92.8%) remained asymptomatic upon discharge. Only 9 (7.2%) subjects developed mild symptoms after admission. Seven subjects had abnormal chest radiograph suggestive of pneumonia, and 22 subjects (17.6%) were found to have mild liver impairment. None of the asymptomatic subjects required oxygen support, inotropic support or ICU care during admission. Fifteen second generation COVID-19 cases were found transmitted from the asymptomatic group, with an attack rate of 3.9%, which was statistically significantly lower compared to the symptomatic (7.6%) or pneumonia groups (25.7%, p<0.001). In conclusion, asymptomatic COVID-19 patients show excellent clinical outcome. They are infectious but had a lower transmission risk compared with symptomatic or pneumonia patients.

Keywords:
Asymptomatic COVID-19 patients clinical outcome Coronavirus disease 2019 (COVID-19) Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Transmission risk

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