Shares of the New York-based company fell about 5% in extended trading.

Restaurant chains have been forced to lean on sales from online and drive-thru services as the pandemic forces people to avoid crowded places.

Industry bellwether McDonald's on Tuesday said drive-thru accounted for nearly 90% of its quarterly sales.

Shake Shack, however, has just started the process of building its first drive-thru, with plans to open it in 2021.

"In the moment of safety, people want to stay in their cars. That's not going to last forever. But obviously, this country has proven that the drive-through in its old form works," Chief Executive Officer Randall Garutti said.

The company's same-store sales fell about 49% in the second quarter ended June 24, compared with the average analyst estimate of a 43.8% decline.

Excluding items, Shake Shack posted a loss of 45 cents per share, compared with estimates for a loss of 37 cents, according to IBES data from Refinitiv.

Shake Shack said recent countrywide protests would have cost the company about $3.2 million in sales in the latest quarter.

It also said same-store sales fell 39% between June 24 and July 22.

Shake Shack's suburban restaurants outperformed those in urban areas during the period and it expects the trend to continue as long as the pandemic rages on, with some of its bigger markets such as New York, Chicago or Los Angeles expected to remain under pressure.

(Reporting by Praveen Paramasivam in Bengaluru; Editing by Shailesh Kuber and Anil D'Silva)