Can you conduct an effective book promotion campaign during the holiday season? Maybe -- but it will take far more work to get book publicity during the last couple of weeks of December, and the first week of January, than it would during the rest of the year. You'll receive fewer responses from the media decision makers now than you typically would expect.
But does that mean that you shouldn't try? It depends on your tolerance for hard work, which is what book publicity campaigns require. If you don't mind making more phone calls, sending out more emails, and filling out more online forms to garner fewer book promotion opportunities, than go for it. You have the advantage of competing against fewer people than usual who are pitching producers and editors. Also, you have producers and editors with last-minute cancellations who might be inclined to cover your story, or grant you an interview, when ordinarily they wouldn't. On the other hand, the reason fewer people than usual are pitching during the holiday season is because fewer media decision makers than usual are at their posts, so it's a double-edged sword.
For those with a book to promote, think of the holidays as an opportunity to bond with people in the media who have the bad luck to be working now. Or, to those of us who work hard all year long pitching stories to the media, think of this as a good time to be working out a plan for approaching the media after the first of the year -- when newspapers, magazines, radio studios, and television studios are once again fully staffed and ready to go.