While concern over the spread of the H1N1 virus sweeps the country, epidemiologists in New York and a few other cities that were awash in swine flu last spring are detecting very little evidence of a resurgence.

Although flu season will not peak until the weather gets cold, in New York, which was the nation’s hardest-hit city, officials say that flu activity is no higher than it normally is at this time of year and that school attendance is normal.

Last week, Dr. Anne Schuchat, the director of immunization at the federal Centers for Disease Control and Prevention, said, “Most states do have quite a lot of disease right now, and that’s unusual for this time of year.”

But public health officials say there appears to be a pattern of areas that had big outbreaks in the spring, like New York, Boston and Philadelphia, seeing less swine flu now.