Flu activity continues to rise in the U.S., according to new surveillance statistics released by the Centers for Disease Control and Prevention on Friday.
Forty-seven states have now reported widespread influenza activity, according to the CDC's latest FluView report, three more states than officials estimated Wednesday. Two more children have died since last week's report, raising the total to 20 kids who have succumbed to the virus.
The report covers the week of Dec. 30 through Jan. 5, and the CDC releases a revision every Friday.
Twenty-four states and New York City have experienced high influenza activity, with 16 states reporting moderate activity. Last week's report showed high activity in 29 states. A complete look at how your state stacks up can be found on the CDC's website.
From Oct. 1 of 2012 through the report, an estimated 13.3 per 100,000 people were hospitalized with flu. The hardest hit group were adults ages 65 and older. Adults with underlying conditions such as diabetes, heart disease, obesity and lung disease (excluding asthma) were more likely to be hospitalized.
Underlying conditions like asthma, neurological disorders or diseases that weaken the immune system were commonly reported in hospitalized kids; however, more than 40 percent of them did not have an underlying medical condition.
Hospitals around the country have reported influxes of flu patients. In Chicago, several hospitals had to divert ambulances while one Pennsylvania hospital had to set up tents to deal with the extra patients.
Dr. Robert Glatter, an emergency medicine physician at Lenox Hill Hospital in New York City, told CBSNews.com Friday that his hospital set up additional treatment areas for flu patients.
"Many patients seem to have more severe illness this year as opposed to last year," Glatter said in an email. "In fact, a number of patients have required mechanical ventilation (respirator) due to difficulty breathing. We have also seen a number of children under the age of 5 with severe symptoms including muscle aches along with vomiting."
The CDC does not track adult death rates -- state health departments do -- but about 24,000 die each year from influenza.
The CDC said the predominant virus causing flu nationwide is influenza A (H3N2), followed by influenza B viruses. Cases of H1N1, or "swine flu," -- the virus behind a 2009 pandemic -- have rarely been seen.
The CDC also released a new study Jan. 11 in its journal Morbidity and Mortality Weekly Report, that found this year's flu vaccine is about 62 percent effective. That's based on test results collected from 1,155 children and adults who reported to doctors with respiratory infections.
The agency still says this year's vaccine matches well to the strains that are out there, and recommends everyone over the age of 6 months gets a flu shot.
"However, these early [vaccine effectiveness] estimates underscore that some vaccinated persons will become infected with influenza," wrote the CDC researchers. "Therefore, antiviral medications should be used as recommended for treatment in patients, regardless of vaccination status."
Prescription drugs such as Tamiflu (generic name oseltamivir) and Relenza (generic name zanamivir) are usually prescribed for about five days, although people who are hospitalized may need to take the medicine longer. The drugs can reduce symptoms and shorten the time people are sick by one to two days, in addition to helping prevent more serious flu complications like pneumonia, according to the CDC.