After Slow Start, Flu Season Has Arrived

After a late start, the flu season ball has begun to roll, according to a new report from the Centers  for Disease Control and Prevention.

The CDC said  it has been the slowest start to a flu season in three decades, but the first week of February seemed to change that tune. The percentage of specimens testing positive for influenza rose from 7.6 percent two weeks ago to 10.5 percent last week.

"The increases we are seeing in the number of respiratory samples testing positive for flu should forecast increases in other flu activity indicators in the coming weeks," Lyn Finelli, chief of domestic surveillance for the  CDC's Influenza Division, said in a statement.

Still, most of the country hasn't seen the flu's full effects yet. Flu season can start as early as October and can last until May, and the timing of the season is quite unpredictable, according to the report.

The western states have seen a small increase in flu activity, but the Northeast and Midwest are reporting  minimal cases of flu. California is the first state to report widespread influenza  this season.

ABC News reached out to several experts on influenza. A few reported seeing more of types of viral activity aside from influenza, but it is unclear whether this indicates  true prevalence;  it might just be more noticeable because there are fewer flu cases this year.

"We have had several other viruses, [including] rhinovirus, coronavirus and metapneumovirus," said Dr. Daniel Hinthorn of the infectious disease department at University of Kansas Hospital and Medical Center. "These can have a cold-like illness with some minor fever and aching but not nearly so bad as influenza. So far, there have been few cases of flu and flu-like illness compared to last year."

Also, mild weather patterns may be a factor in the mild or late start to the season, experts said.

In New York, Dr. Tracy Zivin-Tutela of the infectious disease department at St. Luke-Roosevelt Hospital said the hospital had seen a bigger surge in gastrointestinal viruses.

Nevertheless, "I would not count the flu out yet for the season," said Zivin-Tutela. "It is possible we will see a delay in the surge of flu activity due to the mild winter.  We could start to see a spike in March or even later."

Still, flu season is far from over, and experts continue to implore people to get  flu shots if they haven't already.  On top of that, hand-washing is key to preventing the flu. If you get the flu, be sure to stay home and away from people while sick.

"It is not too late to get a flu shot, and it's a good idea to get one every year," said Elizabeth Casman, associate research professor at Carnegie Mellon in Pittsburgh. "Getting vaccinated not only protects you but also protects the people you would have infected if you had not been vaccinated and caught the flu."

ABC News' Dr. Fang Bu contributed to this report.