Toilet paper hoarding by Americans -- a cultural oddity that gave rise to funny memes and viral posts at the start of the COVID-19 pandemic -- has returned with a vengeance.

The current third wave of infections sweeping the United States has again launched Americans into a frenzy of toilet paper panic buying. Various U.S. media outlets report almost empty toilet paper shelves in supermarkets and stores from California to New York.

Due to the panicky toilet paper buying, Walmart on Friday said it was "seeing pockets of lower than normal availability" for toilet paper and cleaning supplies in some communities.

The immediate trigger to the latest round of panic buying is the decision by 22 states to impose movement and social restrictions aimed at decreasing the spread of the virus. This move, along with purchase limits imposed by some retailers, ignited the latest round of panic buying.

Among retailers with limited sales of certain items are The Kroger Company, the nation's largest supermarket chain, and Target Corporation, the eighth largest retailer.

Shoppers in a half dozen cities said disinfecting wipes were also sold out at discount retailers like Walmart and Costco, as well as at Albertsons and Vons.

"Walmarts are still mostly out of Lysol wipes, and toilet paper is out again," said Whitley Hatcher from Arizona to Reuters.

"Oddly though, at places like Walgreens and Dollar Tree you can find what you need. I think people are seeing the empty shelves at bigger stores and panic buying."

Indications are this toilet paper frenzy isn't as bad as the original one back in March. At the time, media outlets reported a run on toilet paper rolls, and both Costco and the Giant supermarket chain were all but stripped clean of this item.

As to why Americans are reacting to COVID-19 by hoarding toilet paper, one answer is that this product has an almost obsessive association with cleanliness in the minds of most Americans. This means one can't be truly "clean" unless one uses toilet paper.

"There is comfort in knowing that it's there," said psychologist Mary Alvord, Associate Professor of Psychiatry and Behavioral Sciences at the George Washington University School of Medicine. "We all eat and we all sleep and we all poop. It's a basic need to take care of ourselves."

"We've gone beyond using leaves," noted Alvord. "It's about being clean and presentable and social and not smelling bad."

The disappearance of toilet paper anew comes amid a crushing wave of new coronavirus infections, hospitalizations, and deaths sweeping the U.S. The country is reeling from 11.8 million confirmed cases since the pandemic began and 254,000 deaths, according to records of the U.S. Centers for Disease Control and Prevention (CDC). This agency also reported 192,700 new cases on Saturday alone, as well as 1.15 million cases over the last seven days.

Health experts report infections raging virtually unchecked across most of the United States, especially in rural areas in Republican Midwestern states.

The U.S. first exceeded 100,000 new COVID-19 cases per day only on November 3, Election Day. Infections have kept climbing to new all-time highs since. To add to this misery, hospitals in at least 25 states are critically short of health care workers to attend to the swelling of patients.

Taken together, this grim flood of news from the COVID-19 front is triggering a new panic buying frenzy nationwide.