China announced the transmission route of the Delta variant

China announced the transmission route of the Delta variant - Photo 1.

People wait to take PCR samples in Guangzhou city, Guangdong province, China on May 26, 2021 – Photo: GETTY IMAGES

On September 15, the Global Times Reportedly, a group of leading Chinese epidemiologists, including scientist Zhong Nanshan, has mapped the complete transmission chain of the Delta variant for the first time in the world.

This study was published in the journal ClinicalMedicine belong prestigious international medical journal The Lancet. The study is expected to provide reliable data for Delta variant prevention and control measures.

Chinese epidemiologists conducted a study based on the outbreak caused by the Delta variant in Guangzhou city, Guangdong province, southern China. This outbreak started on May 21, 2021 and was brought under control in June.

The team combined viral genetic sequencing and epidemiology technologies to precisely map the complete transmission sequence of the Delta variant. They also incorporate clinical sources.

The researchers found that during the Guangzhou outbreak, the epidemic was mainly transmitted through direct and close contact, with 30.8% of cases of infection through shared meals, followed by family contact. (30.13%), community transmission (18.59%) and other transmission routes including work and social contact (19.87%).

According to the above study, the Delta variant has a shorter incubation period and a faster transmission rate, with an average incubation period of only 4.7 days, significantly shorter than the parent strain (6.3 days). ).

Chinese experts divide infections into generations. Variant Delta can spread across four generations of infections in 10 days, with the fastest intergenerational transmission taking less than 24 hours. The viral load in people with the Delta variant was significantly higher than in the parent strain.

The above study shows that the rapid tracing, isolation and timely detection of infected people, timely management and control in key locations, and PCR testing of all people in some areas in the country. Special circumstances play an important role in preventing the spread of Delta variants.


Transmission network of Delta variant in Guangzhou city. Including the words Generation (generation), G1 (1st generation), G2 (2nd generation), Transmission (transmission), Dining together (eating together), Household (in the family) , Community (in the community), Other (other transmission routes), Critical (critical), Severe (severe, severe), Guangzhou (Guangzhou), Others (other cities) – Photo: THE LANCET

A total of 157 COVID-19 patients are shown in the above transmission network. Each generation of infections is represented as a diamond or a circle with different colors.

The first-generation patient (rhomboid with solid black line, G1) is centrally located. G1 is associated with an imported case (rhomboid with red dotted line, G0).

The colored arrows indicate different routes of transmission, including eating together, in the household, in the community (talking, meeting, taking the elevator together) and other routes (work and communication). social contact).

Patients with severe symptoms (dotted lines) and critically ill patients (solid lines) are shown by squares. Asterisk

indicates whether the patient is in or going to other cities.

This outbreak has been successfully controlled within 7 generations of infections.


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