Exploring secondary SARS-CoV-2 transmission from asymptomatic cases using contact tracing data.
Theor Biol Med Model
; 18(1): 12, 2021 07 16.
Article
in English
| MEDLINE | ID: covidwho-1314267
ABSTRACT
BACKGROUND:
Individuals with asymptomatic severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection can propagate the virus unknowingly and thus have been a focus of public health attentions since the early stages of the pandemic. Understanding viral transmissibility among asymptomatic individuals is critical for successful control of coronavirus disease 2019 (COVID-19). The present study aimed to understand SARS-CoV-2 transmissibility among young asymptomatic individuals and to assess whether symptomatology was associated with transmission of symptomatic vs. asymptomatic infections.METHODS:
We analyzed one of the first-identified clusters of SARS-CoV-2 infections with multiple chains of transmission that occurred among university students in March 2020 in Kyoto prefecture, Japan, using discrete and two-type branching process models. Assuming that the number of secondary cases resulting from either primary symptomatic or asymptomatic cases independently followed negative binomial distributions, we estimated the relative reproduction numbers of an asymptomatic case compared with a symptomatic case. To explore the potential association between symptomatology and transmission of symptomatic vs. asymptomatic incident infections, we also estimated the proportion of secondary symptomatic cases produced by primary symptomatic and asymptomatic cases.RESULTS:
The reproduction number for a symptomatic primary case was estimated at 1.14 (95% confidence interval [CI] 0.61-2.09). The relative reproduction number for asymptomatic cases was estimated at 0.19 (95% CI 0.03-0.66), indicating that asymptomatic primary cases did not result in sufficient numbers of secondary infections to maintain chains of transmission. There was no apparent tendency for symptomatic primary cases to preferentially produce symptomatic secondary cases.CONCLUSIONS:
Using data from a transmission network during the early epidemic in Japan, we successfully estimated the relative transmissibility of asymptomatic cases of SARS-CoV-2 infection at 0.22. These results suggest that contract tracing focusing on symptomatic index cases may be justified given limited testing capacity.Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Contact Tracing
/
COVID-19
Type of study:
Observational study
Limits:
Humans
Country/Region as subject:
Asia
Language:
English
Journal:
Theor Biol Med Model
Journal subject:
Biology
/
Medicine
Year:
2021
Document Type:
Article
Affiliation country:
S12976-021-00144-Z
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