NEW YORK — As the threat of a worldwide swine flu pandemic emerged last month, drug chains and suppliers across North America readied themselves for a possible rush on hygiene products and prescription drugs.

At CVS Caremark Corp., for instance, a spokesman said the 6,900-store chain was stocking up on hand sanitizers, face masks and antibacterial soap.

In New York City, where the first cases of flu in the United States were found, CVS ordered additional doses of Roche Holding AG’s antiviral drug Tamiflu.

A spokesman for Walgreen Co. notes that the growing number of cases of swine flu — formally known as the H1N1 virus — led the retailer to call emergency meetings with many of its suppliers to ensure that the drug chain can meet a surge in demand for such personal hygiene products as hand sanitizers and face masks.

The drug stores took their preparatory steps as the number of confirmed H1N1 cases continued to increase in every corner of the globe.

By the first week of May there were more than 400 confirmed cases in the United States, with people in 38 states being affected. According to the Centers for Disease Control, New York had the highest number of confirmed cases with 97, followed by Illinois with 82. Meanwhile, 49 cases were confirmed in California, 41 in Texas and 20 in Delaware.

In Canada there were 201 confirmed cases. Drug stores there were taking many of the same precautions as their U.S. counterparts.

For the most part, retailers and health care officials in both countries feel the worst of the current outbreak is over for now, but they admit that the virus could reemerge with a vengeance this winter.

“Because the world is reacting better than it did with SARS, the swine flu has been well contained,” says London Drugs president and chief executive officer Wynne Powell, who also is the chairman of the British Columbia Health Services Authority. “However, getting that same level of cooperation if it comes back may not be as easy.”

Medical experts note that in past flu pandemics the virus first hits in the spring and summer and then roars back during the winter flu season.

“If we were just to bet on the odds, we would bet H1N1 would abate in the summer and return in the winter,” Dr. William Schaffner, chairman of preventive medicine at Vanderbilt University School of Medicine in Tennessee, recently told The Baltimore Sun.

Most of the confirmed cases in the United States and Canada have been much more mild than the cases in Mexico, where the virus is believed to have originated. Medical experts wonder if that will continue to be the case if there is a second outbreak later this year.

“The question would be, as it circulates among humans in the Southern Hemisphere [during their winter flu season], could it pick up a virulence gene that is capable of producing severe disease?” Schaffner says. “Influenza is surprising. Its behavior is very difficult to predict.”