The coronavirus is taking a big bite out of Denny's  (DENN) - Get Report business, with the restaurant chain reporting a more than 70% plunge in same-store sales to start the second quarter.

Shares of Denny's at last check fell 8.6% to $10.06 after the Spartanburg, S.C.,  chain offered an estimate on its first-quarter earnings and for April, the first month of the second quarter. The company is set to report for Q1 on May 14.

First-quarter same-store sales fell 6.3% compared with the first three months of 2019, Denny's said. The drop coincided with the rollout in mid-March of social-distancing rules and stay-at-home orders and advisories in states across the country.

But heading into the second quarter, Denny's estimated an average 76% plunge in orders in April as social distancing intensified amid the mounting toll of covid-19.

Same-store sales saw their biggest decline in the first week of April, when they plummeted 79%, with a steady easing over the next three weeks leading to a 72% drop in the month's final week.

"The covid-19 pandemic and various related government mandates restricting dine-in restaurant service have continued to disrupt domestic and international operations for Denny's Corp. and its franchisees," the company said in a statement.

Roughly three-quarters of Denny's restaurants were operating only on a takeout or delivery basis as of May 1, the company said.

Meanwhile, the average volume of takeout and delivery orders has more than doubled, boosted in part by a temporary waiving of delivery fees, Denny's said.

At Dec. 25, 2019, Denny's had 1,703 franchised, licensed and company-owned restaurants worldwide.