Northerner
Admin (Retired)
- Relationship to Diabetes
- Type 1
As few as 10% of people are responsible for 80% of transmission – and that must shape how we tackle this virus.
In February, when Covid-19 was just beginning to spread around the world, a single infected individual exposed as many as 1,100 people in Daegu, South Korea, possibly infecting hundreds. This “superspreading event” sparked a cluster of transmission that eventually grew to more than 5,000 cases in a country recognised as having one of the most effective Covid-19 control programmes to date.
At first glance, this seems wildly inconsistent with what we know about how efficiently Sars-CoV-2 (the virus that causes Covid-19) transmits. The average number of infections caused by someone infected with Sars-CoV-2 – a value known as R – is thought to be between two and five if there is no immunity in the population. How, then, could this one individual, known as “patient 31” by health officials, infect so many?
Though exceptional, the South Korea cluster is just one of many large transmission events that have occurred during the pandemic. We’ve repeatedly seen clusters of 10, 20, or even 50 cases caused by a single individual – far greater than would be indicated by R. This is because R is only an average, and this average masks an interesting phenomenon that has been the subject of growing public interest in recent weeks. It’s known in scientific circles as “overdispersion”. But what exactly is it, and how can an understanding of it translate into action?
www.theguardian.com
In February, when Covid-19 was just beginning to spread around the world, a single infected individual exposed as many as 1,100 people in Daegu, South Korea, possibly infecting hundreds. This “superspreading event” sparked a cluster of transmission that eventually grew to more than 5,000 cases in a country recognised as having one of the most effective Covid-19 control programmes to date.
At first glance, this seems wildly inconsistent with what we know about how efficiently Sars-CoV-2 (the virus that causes Covid-19) transmits. The average number of infections caused by someone infected with Sars-CoV-2 – a value known as R – is thought to be between two and five if there is no immunity in the population. How, then, could this one individual, known as “patient 31” by health officials, infect so many?
Though exceptional, the South Korea cluster is just one of many large transmission events that have occurred during the pandemic. We’ve repeatedly seen clusters of 10, 20, or even 50 cases caused by a single individual – far greater than would be indicated by R. This is because R is only an average, and this average masks an interesting phenomenon that has been the subject of growing public interest in recent weeks. It’s known in scientific circles as “overdispersion”. But what exactly is it, and how can an understanding of it translate into action?
Understanding how ‘overdispersion’ works is key to controlling Covid | Kyra Grantz and Justin Lessler
A small number of people and events are responsible for most virus transmission – that is why tracing them is so vital, say Kyra Grantz and Justin Lessler of the Johns Hopkins Bloomberg School of Public Health
www.theguardian.com
