- case definition
- how sites were determined
- model used
- mathematical methods for model

Methods for First-wave COVID-19 transmissibility and severity in China outside Hubei after control measures, and second-wave scenario planning: a modeling impact assessment

- At least 235 (56%) of 417 cases reported in Shenzhen were from clusters
- 80% of these clusters were among households


University of Michigan - Ann Arbor

Cluster transmission has been noted in many COVID-19 studies
It is characterized by infections that are concentrated within a given area, often within families or social circles 

Cluster Transmission of COVID-19

Leung, K., Wu, J., Liu, D., & Leung, G. (2020). First-wave COVID-19 transmissibility and severity in China outside Hubei after control measures, and second-wave scenario planning: a modelling impact assessment. The Lancet. doi: 10.1016/s0140-6736(20)30746-7

https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30746-7/fulltext

First-wave COVID-19 transmissibility and severity in China outside Hubei after control measures, and second-wave scenario planning: a modelling impact assessment.

Family clustering occurred for all infected infants. 
Families of all 9 infants had at least one infected family member.
All infants' infections occurred after the family member's infection.

Family Clustering of Cases of COVID-19 in Infants in China

Of the 262 patients, 176 (67.2%) were defined as clustered cases, 133 (50.8%) were considered family cluster cases, and 43 (16.4%) were classified as “other” clustered cases. Median cluster size was 3.

Clustering of COVID-19 Cases in Beijing, China

Cluster Transmission of COVID-19 References by Journal

- Asia
- Africa
- North America
- South America
- Antarctica
- Europe
- Australia

Classification of studies on COVID-19 Cluster Transmission by Continents

Cluster transmission in First-wave COVID-19 transmissibility and severity in China outside Hubei after control measures, and second-wave scenario planning: a modeling impact assessment

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