Jefferson (hamstring) isn't practicing Wednesday, Kevin Seifert of ESPN.com reports.
The Vikings continue to take a cautious approach with Jefferson as he recovers from the mild left hamstring strain that he sustained July 24. As recently as last Friday, though, he was spotted working out with trainers on a side field, indicating he at least has made some progress. Whether or not Jefferson makes an appearance in the preseason may be contingent on second-year QB J.J. McCarthy getting into another exhibition beyond this Saturday's matchup with the Texans. Ultimately, ensuring Jefferson is healthy by Week 1 is Minnesota's primary priority.