Impact of age on the likelihood of contact with a contagious person

Canadian Science Publishing
Published in
2 min readJul 9, 2024
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The COVID-19 pandemic has shown how public health measures can slow the spread of contagious diseases. Initially, the level of action needed to control the situation was not yet known. However, governments still had to put in place measures of control, and many opted to close buildings and limit group sizes.

To help with such decisions, we developed a model that estimates how likely someone is to have been in contact with a contagious person. The calculation is based on the activities done over the previous weeks and the spread of disease in the population.

It also considers how age affects the likelihood of contact, which is the new element introduced by our model.

Read this open access paper on the FACETS website.

The model shows that the impact of age varies depending on the spread of disease and the number of people met during activities.

For it to be important, there must be a large difference in spread between age groups. This was the case early in the COVID-19 pandemic, when adults were a lot more likely to be infected than children or the elderly. Even then, age only plays a significant role when the likelihood of contact is moderate.

When the likelihood is very low or very large, the impact of age is not as important.

We present two examples that show how the model can be used to inform public health measures. The first one looks at the impact of capacity restrictions at restaurants. The second one shows how to use it to decide which activities to limit, if needed.

Read the paper — Development of an age-adjusted, activity-based contact probability model for infectious diseases by Bryn Hoffman, Brian Gaas, Sara McPhee-Knowles, Steve Guillouzic, and Lisa Kanary.



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