Good Morning Maureen, 

Thank you for contacting the U of M Extension Service. 

Please click on the following link from the U of M Extension Yard and Garden website: 

https://extension.umn.edu/plant-diseases/aster-yellows

Here is another link: https://extension.umn.edu/yard-and-garden-news/aster-yellows

This information states: 

A practical way to avoid having problems with this disease is to grow plants that are not as susceptible to aster yellows. Verbena, salvia, nicotiana, geranium, cockscomb and impatiens are among the least susceptible plants.

Please click on the following link from the Missouri Botanical Garden: https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/insects-pests-and-problems/diseases/viruses/aster-yellows

It is a difficult disease to deal with. As the information indicates, good cultural practices, weeding and keeping your garden clean. Plant flowers that are not as susceptible to the disease.

I do not know if it affects creeping thyme. 

Good Luck!