By using data from epidemiological investigations and contact-tracing efforts during the initial phase of the coronavirus disease (COVID-19) epidemic in France, researchers were able to appraise secondary clinical attack rates and factors associated with the risk of a contact becoming a case. Their findings are currently available in a medRxiv* preprint paper.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a causative agent of the COVID-19 pandemic, has spread rapidly across the world since it emerged in Wuhan, China. The main reason is its swift spread from person to person via the respiratory route.
During the early phase of the epidemic, France made a substantial effort to contain the virus’s importation into its territory. In January 2020, a steadfast surveillance system was already implemented country-wide that enabled early detection of cases and contacts but also slowed the spread of the virus and halted secondary transmission events.
Such contact tracing represents an indispensable tool for controlling epidemics and has proven efficient in the past. However, its use can also improve the knowledge on the natural history of emerging pathogens (such as SARS-CoV-2) and their transmission dynamics.
Consequently, a French group of researchers, led by Dr. Paireau Juliette from the Institute Pasteur in Paris, aimed to assess secondary clinical attack rates and to pinpoint risk factors that play a role in contacts becoming cases, but also to estimate chains of transmission and key parameters of viral spread.