SAN FRANCISCO (CBS SF/AP) — The winter flu season is off to its earliest start in more than 15 years around the country including in California where there have already been 16 flu-related deaths, health officials.

State Public Health Officer Dr. Sonia Angell warned residents to get their flu shots as soon as possible.

READ MORE: Lowell High School Alumni File Lawsuit To Reinstate Merit-Based Admissions

“Flu activity is starting earlier than usual in California this season,” Angell said in a news release. “The flu shot protects you and those around you by making it less likely you’ll get sick if you’re exposed to the virus, and if you do get ill, you’ll tend to have fewer days of symptoms and they’ll be less severe.”

Since September 29th when the flu season started, there have been 16 flu-related fatalities identified on death certificates. In addition, two influenza-associated deaths in children under the age of 18 have been reported to the state health department.

Federal health officials said the last flu season to rev up this early was in 2003-2004 and it was bad one.

“It really depends on what viruses are circulating. There’s not a predictable trend as far as if it’s early it’s going to be more severe, or later, less severe,” said Scott Epperson, who tracks flu-like illnesses for the U.S. Centers for Disease Control and Prevention.

There are different types of flu viruses, and the one causing illnesses in most parts of the country is a surprise. It’s a version that normally doesn’t abound until March or April.

READ MORE: Environmental Whistleblower Sets Off Probe Into Illegal Discharge Of Petcoke At Port Of Benicia

That virus generally isn’t as dangerous to older people since most flu hospitalizations and deaths each winter occur in the elderly. However, such viruses can be hard on children and people younger than 50.

Louisiana was the first state to really get hit hard, with doctors there saying they began seeing large numbers of flu-like illnesses in October.

Children’s Hospital New Orleans has already seen more flu cases this fall than it saw all of last winter, said Dr. Toni Gross, the hospital’s chief of emergency medicine. Last month was the busiest ever at the hospital’s emergency department. Officials had to set up a triage system and add extra shifts, Gross said.

“It is definitely causing symptoms that will put you in bed for a week,” including fever, vomiting and diarrhea. But the hospital has not had any deaths and is not seeing many serious complications, she said.

The CDC estimates that there have already been 1.7 million flu illnesses, 16,000 hospitalizations, and 900 flu-related deaths nationally.

The most intense patient traffic had been occurring in a six states stretching from Texas to Georgia. But in new numbers released Friday, CDC officials said the number of states with intense activity rose last week to 12. Flu is widespread in 16 states, though not necessarily at intense levels in each, the CDC said.

MORE NEWS: COVID: UCSF Researchers Examine Impact Of Coronavirus On Young Brains After 3 Teens Develop Psychosis

Last flu season started off as a mild one but turned out to be the longest in 10 years. It ended with around 49,000 flu-related deaths and 590,000 hospitalizations, according to preliminary estimates.