key: cord-0821822-jhp84m0o
authors: Yi, Seonju; Kim, Young-Man; Choe, Young June; Ahn, Seonhee; Han, Sohee; Park, Young-Joon
title: Geospatial Analysis of Age-specific SARS-CoV-2 Transmission Patterns in Households, Korea
date: 2021-02-22
journal: J Korean Med Sci
DOI: 10.3346/jkms.2021.36.e63
sha: 8bccbdbb9755e7ff158c602673663c019bb00d16
doc_id: 821822
cord_uid: jhp84m0o

We constructed an age-to-age infection matrix to characterize the household transmission pattern of coronavirus disease 2019 (COVID-19) in Korea. Among 4,048 household clusters, within-age group infection dominated the overall household transmissions. Transmission of severe acute respiratory syndrome coronavirus 2 was more common from adults to children than from children to adults.

infecting an average of 1.57 household members. Fig. 1 shows age-to-age infection matrix with crude number and gradation by scale. In general, the infection matrix indicates that within-age group infection dominated the overall household transmissions. Infection from parents (or guardians) aged 30-49 to children aged 0-14 occurred in 455 events, whereas infection from children to parents (or guardians) occurred in 123 events. Among people aged 65 years and older (n = 734), 48.9% were infected from aged 65 years and older, while children aged 0-14 years accounted for 4.9% of the infections in this age group. Fig. 2 shows the distribution of infector (index case) and infectee (secondary case) by age groups. The highest proportion of infectors (index case) in the households were adults aged 45-49 years (391/4,088; 11.1%), followed by 55-59 years (397/4,088; 9.7%) and 40-44 years (391/4,088; 9.6%). The highest proportion of infectees (secondary case) in the households were adults aged 50-54 years (381/4,088; 9.3%), followed by 60-64 years (357/4,088; 8.7%), and 55-59 years (324/4,088; 7.9%).

There are limitations to this study. First, we did not obtain the time of onset for infectorinfectee pairs, therefore the direction of transmission may be hypothetical. Second, given the low number of testing in the childhood population, the detection bias among this age group may limit the result of this study. There had been reports on transmission within daycare centers during the observed period, which may not have been ascribed in this study. Third, we have not included geographical and detection time differences for infector-infectee pairs in this study, which limits description of the result. Despite these limitations, this study Transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was more common from adults to children than from children to adults. 5 This underscores the importance of additional awareness targeting the adult population and reappraises the implication of school closure on SARS-CoV-2 transmission in the households.

Dr. Seonju Yi is an epidemiologist at Korea Disease Control and Prevention Agency, specializing in infectious disease epidemiology and quantification of the surveillance data. 

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