A report highlighting the county-level housing markets most vulnerable to the coronavirus pandemic said pockets of the northeast and other parts of the East Coast were most at risk during the fourth quarter.

ATTOM Data Solutions’ fourth-quarter 2020 Special Coronavirus Report said clusters in the New York City and Philadelphia areas are most vulnerable, while the West continued to be less vulnerable.

 According to the report, New Jersey, Illinois, California, Louisiana, New York, Florida, and Maryland had 40 of the 50 counties most vulnerable to the economic impact of the pandemic in the fourth quarter of 2020. Eight suburban counties in the New York City metropolitan area, four around Philadelphia, and two near Washington, D.C. were considered most vulnerable. Also high on that list were six counties in the Chicago area and two near St. Louis.

ATTOM said what markets are considered more or less at risk is based on the percentage of homes facing possible foreclosure, the portion with mortgage balances that exceed the estimated property value, and the percentage of average local wages required to pay for major home ownership expenses.

“Areas of the U.S. most at risk from damage connected to the coronavirus pandemic spread out somewhat in the fourth quarter of 2020. But they still fell mainly along the East Coast, with significant pockets in certain areas, while other parts of the country seem to be less vulnerable,” ATTOM Chief Product Officer Todd Teta said in a release.

“This report is not a sign that any area actually took a fall in the fourth quarter. It’s more a gauge of areas that may be more vulnerable if the market falters,” Teta said. “In the coming months, much will depend on whether the country can halt the pandemic. We will continue to keep a close watch on home sales and prices to see how everything shakes out in 2021 and if changes hit different regions in different ways.”

Five of the seven western counties in the top 50 during (most vulnerable) the fourth quarter were in northern California. Outside of Florida and Maryland, the only southern state with more than two counties in the top 50 was Louisiana.

ATTOM said 18 of the 50 counties least vulnerable to pandemic-related problems were in Colorado, Massachusetts, Minnesota, and Texas. They were concentrated in the Denver, Boston, Minneapolis, Houston, and Dallas metro areas. The largest of the 50 least at-risk counties were Harris County (Houston); King County (Seattle); Clark County (Las Vegas); Tarrant County (Fort Worth), Texas; and Middlesex County, Mass. (outside Boston).