<abstract xmlns="http://www.w3.org/1999/xhtml">

<sec><h3>Background</h3>
<p>In Japan, on April 20, 2020, the definition of a close contact regarding coronavirus disease (COVID-19) was changed from a long-term contact time to a specified contact time of 15 min and from a contact distance of 2 m to 1 m.</p>
</sec>
<sec><h3>Objectives</h3>
<p>We aimed to determine the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection rate among close contacts of patients with COVID-19 and determine the impact of the infection on transmission among close contacts.</p>
</sec>
<sec><h3>Methods</h3>
<p>The numbers of SARS-CoV-2 tests, SARS-CoV-2-positive cases, and close contacts of patients with COVID-19 were assessed between March 2020 and February 2021 in Fukui Prefecture, Japan. The study period was subdivided into 3 periods. The second and third period contained data with the changed definition of close contact.</p>
</sec>
<sec><h3>Results</h3>
<p>Overall, 32,238 SARS-CoV-2 tests were performed. There were 545 patients with COVID-19 and 1487 close contacts, of whom 267 tested positive. The highest infection rate occurred in period 3. Distance, protective measures, and contact time with COVID-19 patients influenced the increased infection rate. The infection rate showed a rising trend from 11.1% in period 1 to 19.2% and 20.0% in periods 2 and 3, respectively (Cochran–Armitage test; <italic>P</italic> &lt; 0.004). Multivariate analysis revealed that female sex was an independent risk factor for infection of close contacts (odds ratio: 2.23; 95% confidence interval: 1.700–2.930).</p>
</sec>
<sec><h3>Conclusions</h3>
<p>Female sex is a risk factor for transmission by close contacts. The rate of infection among close contacts may be associated with contact time, contact distance, and protective measures.</p>
</sec>
</abstract>

Background
In Japan, on April 20, 2020, the definition of a close contact regarding coronavirus disease (COVID-19) was changed from a long-term contact time to a specified contact time of 15 min and from a contact distance of 2 m to 1 m.

Objectives
We aimed to determine the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection rate among close contacts of patients with COVID-19 and determine the impact of the infection on transmission among close contacts.

Methods
The numbers of SARS-CoV-2 tests, SARS-CoV-2-positive cases, and close contacts of patients with COVID-19 were assessed between March 2020 and February 2021 in Fukui Prefecture, Japan. The study period was subdivided into 3 periods. The second and third period contained data with the changed definition of close contact.

Results
Overall, 32,238 SARS-CoV-2 tests were performed. There were 545 patients with COVID-19 and 1487 close contacts, of whom 267 tested positive. The highest infection rate occurred in period 3. Distance, protective measures, and contact time with COVID-19 patients influenced the increased infection rate. The infection rate showed a rising trend from 11.1% in period 1 to 19.2% and 20.0% in periods 2 and 3, respectively (Cochran–Armitage test; P < 0.004). Multivariate analysis revealed that female sex was an independent risk factor for infection of close contacts (odds ratio: 2.23; 95% confidence interval: 1.700–2.930).

Conclusions
Female sex is a risk factor for transmission by close contacts. The rate of infection among close contacts may be associated with contact time, contact distance, and protective measures.

Infection rate among close contacts of patients with coronavirus disease in Japan: a descriptive study and literature review

Department of Community Medicine, Faculty of Medical Sciences

Department of Infectious Diseases, Faculty of Medical Sciences

Department of Biostatistics, Faculty of Medical Science

Department of Infection Prevention and Control

Asian Biomedicine

This work is licensed under the Creative Commons Attribution 4.0 International License.

Background
In Japan, on April 20, 2020, the definition of a close contact regarding coronavirus disease (COVID-19) was changed from a long-term contact time to...

Infection rate among close contacts of patients with coronavirus disease in Japan: a descriptive study and literature review

Article Category: Original article

Online veröffentlicht: 09. Okt. 2023

Seitenbereich: 115 - 123

DOI: https://doi.org/10.2478/abm-2023-0051

Schlüsselwörter
close contact infectious disease transmission, contact time, COVID-19, protective measures, social distancing

© 2023 Osamu Yamamura et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Infection rate among close contacts of patients with coronavirus disease in Japan: a descriptive study and literature review

Article Category: Original article

Online veröffentlicht: 09. Okt. 2023

Seitenbereich: 115 - 123

DOI: https://doi.org/10.2478/abm-2023-0051

Schlüsselwörterclose contact infectious disease transmission, contact time, COVID-19, protective measures, social distancing

© 2023 Osamu Yamamura et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Schlüsselwörter
close contact infectious disease transmission, contact time, COVID-19, protective measures, social distancing