Flu season has latest start in 27 years

U.S. hospitals marked a slight increase in influenza activity during the first week in February, marking the beginning of the flu season.

A report by the U.S. Centers for Disease Control and Prevention said that in the last 29 years, only one other flu season began so late, and that was 27 years ago, according to MSNBC.

"This pattern is unusual, but not unprecedented," Dr. Joseph Bresee, the chief of the epidemiology and prevention branch at the CDC, said, MSNBC reports. "If you haven't gotten you flu vaccine yet, get your vaccine now- it's not too late."

The CDC reports that the majority of the flu viruses in circulation now are similar to the one making up this year's vaccine. Vaccinations are recommended for those six months and older in the United States.

Bresee said that the late start to the flu season may be attributable, at least in part, to rising flu vaccination rates. As of November 2011, more people were vaccinated than in November 2010.

"As vaccine coverage increases, we ought to see less disease in the United States," Bresee said, according to MSNBC.

In addition, according to Bresee, the viruses circulating now are similar to the ones that were circulating last year, so there may be some immunity carried over from last season.

Researchers have yet to be able to predict the length of flu season, or when it will peak.