The fast spreading Delta variant has prompted some fast-food chains like McDonald's to consider closing indoor seating areas or limit restaurant hours, according to franchisees.

Last week, McDonald's instructed its restaurant operators on steps they should take to once again close dining rooms in parts of the country with high infection rates, according to internal company material seen by Reuters.

It's not yet clear how many locations will be impacted.

This now puts a halt to the global hamburger chain's plan to have nearly 100 percent of its U.S. locations open for indoor dining by Labor Day. It had reopened 70 percent by last month after temporarily closing nearly all sit-down areas when the pandemic first hit in early 2020.

One McDonald's franchisee who operates multiple locations isn't taking any chances and told Reuters it has already barred indoor seating at several locations.

Other fast-food chains are impacted as well. PMTD Restaurants, which operates nearly 40 KFC and Taco Bell locations, said it has had to cut hours in Georgia and Alabama after several employees became infected with COVID-19 - leading to a staff shortage.

Instead of closing some of its Taco Bell locations at midnight, it's closing at 8 p.m... not an easy decision to make. The president of the restaurant group said late-night customers can make up to 20 percent of that operator's daily sales.