TUESDAY, Feb. 3 (HealthDay News) -- There are far fewer cases of flu in the United States so far this year compared to last year, a sign that the nation may be in for a relatively mild flu season, experts said Tuesday.

But, the experts also said they're keeping a close watch on bacterial infections such as methicillin-resistant Staphylococcus aureus (MRSA). MRSA is resistant to certain antibiotics and can strike flu patients -- particularly hospitalized ones -- and is potentially fatal.

"The influenza activity we have seen in the United States has been relatively mild in comparison to last season," Nancy Cox, director of the U.S. Centers for Disease Control and Prevention's Influenza Division, said during a teleconference.

So far, the states with the most cases of flu are New Jersey and Virginia, Cox said, adding that hard numbers are difficult to come by, so health officials are relying on anecdotal reports.

The number of patients with flu that doctors are seeing is also well below the seasonal baseline. The national baseline is about 2.4 percent -- the percent of patients with flu symptoms seen by doctors, Cox said.

"That is unusual for this time of year and is indicative of a relatively mild influenza season," she said.

Also, deaths from pneumonia associated with influenza are well below the epidemic level, Cox said.

The most common flu virus this year is influenza A -- primarily the H1 viruses, Cox said. This is one of the groups of viruses included in this year's flu vaccine, she said, adding that the vaccine also includes AH3 and influenza B viruses.

Cox noted that the H1 strains of the influenza virus are resistant to the commonly used antiviral medication Tamiflu.