The storm, which caused upwards of $50 billion in damage, could affect the figures for the better part of a month, according to the officials.
The total number of people claiming benefits in all programs for the week ending Oct. 27 was 4.97 million, a decrease of 100,423 from the previous week, compared with 6.77 million a year ago.
Before Sandy hit most of the East Coast on Oct. 29, first-time claims had been running steady all year, with only a couple of larger fluctuations in the data.
Still, the job market has begun showing signs of improvement as employers added 171,000 jobs in October and the unemployment rate increased slightly, to 7.9 percent, as more people joined the workforce.
There are other signs that the recovery is gaining a foothold, with economic growth in the third quarter expected to come in at a faster pace than initially forecast, possibly around 3 percent, a better showing than the 2 percent reported in October.
The next estimate of gross domestic product is set for release shortly after the Thanksgiving holiday, Nov. 29.
A separate report on Wednesday showed a drop in retail sales for October as consumers habits likely reflected broader concerns about the presidential election as well as the looming spending cuts and tax increases that could happen in January if Congress and the White House are unable to forge a short-term deal.