Researchers developed a model for how COVID-19 transmission changes under different conditions and then put together a cool online interactive graphic that displays the amount of risk of getting infected with SARS-CoV-2, and thus getting COVID-19.  You can change 15 settings to see how risk of transmission from the infected person to the noninfected person changes in many different situations.

The model has limitations. You cannot change the viral load of the infected person or the variant of the virus or the susceptibility of the uninfected person. You cannot change vaccination status of the infected or uninfected person.

After playing with the tool a bit, I have a few tips to share.

Tip: Just changing a setting is enough to start the new analysis and show the difference in risk transmission. This can be a bit confusing if there is little change between the first setting and the newly selected setting. There is no need to press “go” or “start”. 

A good example to see a big difference is set the activity to “Coughing” without changing any other settings.

“Reset graphic” restores the settings to the default, not starts the transmission under the selected conditions.

Tip: I initially missed that the color of the uninfected person changes as infection risk increases. So, pay attention to both the flows of the purple pathways and the color of the uninfected person when you change a setting.

Tip: As you select a change in protection, the blue line represents the barrier across the pathways of transmission that the protection provides.

Tip: The little ‘i’ in a circle brings up a window that let’s you read about how the information was determined, provides a 5-star rating of the quality of the evidence, an indication of the confidence of the experts’ estimated values, and what factors contribute to the uncertainty in the estimates.

Highlighted Articles

Rutter H, Parker S, Stahl-Timmins W, Noakes C, Smyth A, Macbeth R et al. Visualising SARS-CoV-2 transmission routes and mitigations. BMJ 375 :e065312 (2021) doi:10.1136/bmj-2021-065312 [This one has the online tool.]

Freeman AL, Parker S, Noakes C, et al. Expert elicitation on the relative importance of possible SARS-CoV-2 transmission routes and the effectiveness of mitigations. BMJ Open 11:e050869 (2021). doi: 10.1136/bmjopen-2021-050869 [This one has the data used to develop the model that drives the tool.]

A direct link to the online tool: https://www.bmj.com/content/375/bmj-2021-065312/infographic

Read more about COVID-19 by Nancy R. Gough