Dataset Information

Variability in transmission risk of SARS-CoV-2 in close contact settings: A contact tracing study in Shandong Province, China.

ABSTRACT:

Background

Understanding the relative transmissibility of SARS-CoV-2 virus across different contact settings and the possibility of superspreading events is important for prioritizing disease control. Such assessment requires proper consideration of individual level exposure history, which is made possible by contact tracing.

Methods

The case-ascertained study in Shandong, China including 97 laboratory-confirmed index cases and 3158 close contacts. All close contacts were quarantined after their last exposure of index cases. Contacts were tested for COVID-19 regularly by PCR to identify both symptomatic and asymptomatic infections. We developed a Bayesian transmission model to the contact tracing data to account for different duration of exposure among individuals to transmission risk in different settings, and the heterogeneity of infectivity of cases.

Results

We estimate secondary attack rates (SAR) to be 39% (95% credible interval (CrI): 20-64%) in households, 30% (95% CrI: 11-67%) in healthcare facilities, 23% (95% CrI: 7-51%) at workplaces, and 4% (95% CrI: 1-17%) during air travel. Models allowing heterogeneity of infectivity of cases provided a better goodness-of-fit. We estimated that 64% (95% CrI: 55-72%) of cases did not generate secondary transmissions, and 20% (95% CrI: 15-26%) cases explained 80% of secondary transmissions.

Conclusions

Household, healthcare facilities and workplaces are efficient setting for transmission. Timely identification of potential superspreaders in most transmissible settings remains crucial for containing the pandemic.

SUBMITTER: Tsang TK

PROVIDER: S-EPMC8906027 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature

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Publications

Variability in transmission risk of SARS-CoV-2 in close contact settings: A contact tracing study in Shandong Province, China.

Tsang Tim K TK Fang Li-Qun LQ Zhang Anran A Jiang Fa-Chun FC Ruan Shi-Man SM Liu Lan-Zheng LZ Cowling Benjamin J BJ Liu Wei W Yang Yang Y

Epidemics 20220309

<h4>Background</h4>Understanding the relative transmissibility of SARS-CoV-2 virus across different contact settings and the possibility of superspreading events is important for prioritizing disease control. Such assessment requires proper consideration of individual level exposure history, which is made possible by contact tracing.<h4>Methods</h4>The case-ascertained study in Shandong, China including 97 laboratory-confirmed index cases and 3158 close contacts. All close contacts were quaranti ...[more]

PMID: 35287110

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Project description:Vector-borne diseases leave a large footprint on global health. Notable culprits include West Nile virus (WNV), St. Louis encephalitis virus (SLEV), and Japanese encephalitis virus (JEV), all transmitted by Culex mosquitoes. Chemical insecticides have been widely used to reduce the spread of mosquito-borne diseases. Still, mosquitoes are becoming more and more resistant to most chemical insecticides which cause particular harm to the ecology. Wolbachia belongs to the family Ehrlichiaceae in the order Rickettsiales and is a matrilineally inherited endosymbiont present in 60% of insects in nature. Wolbachia is capable of inducing a wide range of reproductive abnormalities in its hosts, such as cytoplasmic incompatibility, and can alter mosquito resistance to pathogen infection. Wolbachia has been proposed as a biological alternative to chemical vector control, and specific research progress and effectiveness have been achieved. Despite the importance of Wolbachia, this strategy has not been tested in Culex pipiens pallens, the most prevalent mosquito species in Shandong Province, China. Little is known about how the mass release of Wolbachia-infected mosquitoes may impact the genetic structure of Culex pipiens pallens, and how the symbiotic bacterium Wolbachia interacts with mitochondria during host mosquito transmission. Based on the population genetic structure of Culex pipiens pallens in Shandong Province, this study investigated the infection rate and infection type of Wolbachia in Shandong Province and jointly analysed the evolutionary relationship between the host mosquito and the symbiotic bacterium Wolbachia. Our study showed that Wolbachia naturally infected by Culex pipiens pallens in Shandong Province was less homologous to Wolbachia infected by Aedes albopictus released from mosquito factory in Guangzhou. Our results also show that Culex pipiens pallens is undergoing demographic expansion in Shandong Province. The overall Wolbachia infection rate of Culex pipiens pallens was 92.8%, and a total of 15 WSP haplotypes were detected. We found that the genetic diversity of Wolbachia was low in Culex pipiens pallens from Shandong Province, and the mosquitoes were infected only with type B Wolbachia. Visualizing the relationship between Culex pipiens pallens and Wolbachia using a tanglegram revealed patterns of widespread associations. A specific coevolutionary relationship exists between the host mosquito and Wolbachia. Knowledge of this mosquito-Wolbachia relationship will provide essential scientific information required for Wolbachia-based vector control approaches in Shandong Province and will lead to a better understanding of the diversity and evolution of Wolbachia for its utility as a biocontrol agent.

Project description:BackgroundRisk for transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to close contacts of infected persons has not been well estimated.ObjectiveTo evaluate the risk for transmission of SARS-CoV-2 to close contacts in different settings.DesignProspective cohort study.SettingClose contacts of persons infected with SARS-CoV-2 in Guangzhou, China.Participants3410 close contacts of 391 index cases were traced between 13 January and 6 March 2020. Data on the setting of the exposure, reverse transcriptase polymerase chain reaction testing, and clinical characteristics of index and secondary cases were collected.MeasurementCoronavirus disease 2019 (COVID-19) cases were confirmed by guidelines issued by China. Secondary attack rates in different settings were calculated.ResultsAmong 3410 close contacts, 127 (3.7% [95% CI, 3.1% to 4.4%]) were secondarily infected. Of these 127 persons, 8 (6.3% [CI, 2.1% to 10.5%]) were asymptomatic. Of the 119 symptomatic cases, 20 (16.8%) were defined as mild, 87 (73.1%) as moderate, and 12 (10.1%) as severe or critical. Compared with the household setting (10.3%), the secondary attack rate was lower for exposures in health care settings (1.0%; odds ratio [OR], 0.09 [CI, 0.04 to 0.20]) and on public transportation (0.1%; OR, 0.01 [CI, 0.00 to 0.08]). The secondary attack rate increased with the severity of index cases, from 0.3% (CI, 0.0% to 1.0%) for asymptomatic to 3.3% (CI, 1.8% to 4.8%) for mild, 5.6% (CI, 4.4% to 6.8%) for moderate, and 6.2% (CI, 3.2% to 9.1%) for severe or critical cases. Index cases with expectoration were associated with higher risk for secondary infection (13.6% vs. 3.0% for index cases without expectoration; OR, 4.81 [CI, 3.35 to 6.93]).LimitationThere was potential recall bias regarding symptom onset among patients with COVID-19, and the symptoms and severity of index cases were not assessed at the time of exposure to contacts.ConclusionHousehold contact was the main setting for transmission of SARS-CoV-2, and the risk for transmission of SARS-CoV-2 among close contacts increased with the severity of index cases.Primary funding sourceGuangdong Province Higher Vocational Colleges and Schools Pearl River Scholar Funded Scheme.

Dataset Information

Variability in transmission risk of SARS-CoV-2 in close contact settings: A contact tracing study in Shandong Province, China.

Background

Methods

Results

Conclusions

Publications

Variability in transmission risk of SARS-CoV-2 in close contact settings: A contact tracing study in Shandong Province, China.

Similar Datasets

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