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Studies characterize early chains and patterns of COVID-19 infection in France

Using data from epidemiological studies and contact tracing efforts in the early stages of the coronavirus disease (COVID-19) epidemic in France, researchers have found secondary clinical incidence and contact in cases. I was able to evaluate the factors related to the risk of becoming. Their findings are now medRxiv * Preprint paper.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the causative agent of the COVID-19 pandemic, has spread rapidly around the world since its appearance in Wuhan, China. The main reason is the rapid spread from person to person through the respiratory pathways.

In the early stages of the epidemic, France made great efforts to contain the import of the virus into its territory. In January 2020, a stable surveillance system was already implemented nationwide that not only enabled early detection of cases and contacts, but also slowed the spread of the virus and stopped secondary infection events.

Such contact tracing is an essential tool for controlling epidemics and has proven to be efficient in the past. However, its use can also improve knowledge of the natural history of emerging pathogens (such as SARS-CoV-2) and their infectious dynamics.

As a result, a group of French researchers led by Dr. Paireau Juliette of the Pasteur Institute in Paris will assess secondary clinical incidence and identify risk factors that play a role in contact becoming a case. Was aimed at. An important parameter of virus epidemic.

Chain of transmission. (A) Observed transmission chain. Only confirmed cases / contacts related to the chain with at least one confirmed case are displayed. (B) Gender distribution. (C) Age distribution.

Use a strict monitoring system

In this study, researchers contacted the early stages of the epidemic in France, more specifically, a retrospective outbreak study from January 24, 2020 to March 30, 2020, two weeks after the blockade. We analyzed the detailed data collected during the racing.

The data were used to assess the secondary clinical incidence in detail and to characterize the risk of a contact being a case among the 6,082 contacts of 735 probands. In addition, the chain of infection has been explained, and then key parameters that spread among 328 infected / infected pairs have been estimated.

Protocols and case definitions evolved during the study to adapt to changing epidemics, while new knowledge of SARS-CoV-2 and its transmission emerged. After collection, all the data was entered into a secure web-based application.

Clarify the importance of superspreading

The study found that the overall secondary clinical incidence was 4.1%, which increased significantly with age of probands and contacts. Family contacts had a much higher risk of becoming a case, while hospital contacts had a lower risk than colleagues and friends.

In addition, the distribution of secondary cases was highly dispersed, with 80% of secondary cases caused by only 10% of cases. The average serial interval was 5.1 days for contact tracing pairs, consistent with published estimates of 4-6 days obtained in similar situations of case isolation.

Finally, the average number of secondary cases associated with all probands ranged from 0.3 to 0.9. These values ​​are lower than the estimated SARS-CoV-2 reproductions in the absence of intervention or herd immunity, usually 2.5-3.

Valuable lessons for epidemiologists

This study will definitely contribute to improving knowledge about SARS-CoV-2 infection. In particular, consider the importance of super-spreading events with all the implications of control efforts.

“In our study population, we found that the risk of developing a case was more than twice as high in contacts aged 45 and over compared to those aged 15-29,” stressed the authors of this study. doing. medRxiv paper.

“Interestingly, the age-specific contact patterns observed in our study before the cases were isolated are very consistent with those obtained in a large census conducted in France in 2012. “It was,” they add.

Proper collection and analysis of this type of data, despite the enormous effort required to perform contact tracing during an outbreak event, provides a better understanding of disease transmission and a highly efficient control strategy. Extremely important for adjustment.

*Important Notices

medRxiv Publish preliminary scientific reports that should not be considered definitive as they are not peer-reviewed, guide clinical practice / health-related behaviors, and should not be treated as established information.

Studies characterize early chains and patterns of COVID-19 infection in France

Source link Studies characterize early chains and patterns of COVID-19 infection in France

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