Midsommarfirande Nätverksforskning Foto: Kenneth Kullman/Mostphotos
Kunskap om människors sociala nätverk är viktigt för att förstå hur sjukdomar sprids.
Foto: Kenneth Kullman/Mostphotos.

Fredrik Liljeros had his first research position as a postdoc at the former Institute for Infectious Diseases with current State Epidemiologist Anders Tegell as his direct supervisor and Johan Giesecke, former State Epidemiologist, as his departmental supervisor. At the time, SARS was the focus – a viral outbreak with a higher mortality rate than COVID-19.

Fredrik Liljeros
Fredrik Liljeros
Photo: Paul Fuehrer

"I was honestly more worried about the future back then. Partly because of the high mortality rate but also because Canada lost control over the spread of the disease for a while."


What is network research?

"Network research is an interdisciplinary research field that incorporates sociology, ecology, mathematics and physics. We all map network structures with different questions in mind, like: How did the network emerge? Why does it look like it does? What are the consequences of this?

How is it relevant to studying epidemics?

"There’s a significant variation in how important different types of contact are to spreading different diseases. Some require close contact or contact over a longer period of time, like tuberculosis or HIV. Others are extremely contagious, like measles, where one person can infect a whole lecture hall.

"COVID-19 is a disease that most often requires close contact over a longer time period to be transmitted. According to the first data coming from China, most people were infected by their own family members. Of course, it’s also important to understand the more casual, less infectious contacts outside of the closest circles because there are so many more of them.

"In the battle against transmission, simple mathematical models are often used, where everyone in a group (like a city) is assumed to have the same potential for transmission. The models function surprisingly well for very easily transmitted diseases, but less well for diseases like influenza and COVID-19.

"To understand how diseases like COVID-19 are spread and how they should be fought, we need a deeper knowledge about the structures of people’s networks and contacts. This knowledge allows government agencies to make different types of decisions about what will effectively combat transmission. Unfortunately, a lot of the studies being published now build on overly simplistic assumptions about contact networks."

What is the most important thing learned from earlier epidemics?

– Att det alltid uppstår ryktesspridning. Bland annat om hur sjukdomar smittar. Situationen i samband med covid-19 epidemin skiljer sig från tidigare epidemier genom att sociala medier nu används av i princip alla, gammal som ung. Det gör att rykten sprids lättare än tidigare.

What other topics do network researchers study?

– Allt mellan himmel och jord. Jag har varit inblandad i forskningsprojekt vars syfte är alltifrån att kartlägga bins kontaktmönster i bikupor, dejtingsajter på internet till kriminella nätverk.

What are you researching now?

– Hur kontaktmönster på sjukhus påverkar risken för att sjukdomar sprids inom och mellan olika sjukhus. Men för tillfället går större delen av min tid åt till att kritiskt granska alla relevanta studier som publiceras just nu om covid-19.

Fredrik Liljeros’ current research focus:

  • How infections spread within and among hospitals
  • How human interaction patterns affect the spread of disease
  • Development of mathematical models for how illnesses spread, particularly sexually transmitted diseases
  • Pandemics and studies of how actions like travel restrictions affect the speed of transmission in epidemics.

Read more about Freedrik Liljeros’ research


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