(CNN) - The deadly grip of the flu season appears to be weakening, according to statistics released Friday by the US Centers for Disease Control and Prevention.
During the seventh week of the year, 6.4% of people who visited their doctors complained of flu-like illness, the CDC said in its weekly surveillance report. That number is down from the previous week -- when it was 7.5%. It's the first time this season the number has dropped.
"It's definitely an encouraging sign," said CDC spokeswoman Kristen Nordlund. But Nordlund added that "half of the country is still experiencing high activity and it's still widespread everywhere, so we're still in the thick of it."
"We're just not ready to say that we've peaked yet."
Dr. William Schaffner, an infectious disease specialist at Vanderbilt University in Nashville, Tennessee, predicted, "It will go well into March."
Based on what's happening in his "neck of the woods, Schaffner said, "We're not going up anymore in terms of patients who are hospitalized with lab-confirmed influenza, but we're also not trending down yet."
For the week ending February 17, flu activity remained elevated in most states. Five states, Connecticut, Hawaii, Iowa, Utah, and Wisconsin, reported moderate activity of flu-like illness.
Three states, Florida, Idaho, and Washington, experienced low activity, while three other states, Maine, Montana, and North Dakota, showed only minimal activity. High activity of flu-like illness, though, continued in New York City, the District of Columbia, Puerto Rico and the remaining 39 states.
The CDC reported 13 more flu-related deaths in children, raising the total number of pediatric deaths for the season to 97 as of February 17.
A total of 21,279 confirmed flu-related hospitalizations were reported between October 1, 2017 and February 17, 2018, according to the CDC.
The cumulative rate of flu-related hospitalizations rose to 74.5 people out of every 100,000 in the seventh week of 2018 from nearly 68 out of every 100,000 last week, the CDC estimated in its weekly surveillance report.
These rates varied depending on age with adults age 65 and older hospitalized at the rate of nearly 323 per 100,000 people in that same age group.
There are more older people out there and that contributes to the high hospitalization rates, said Schaffner.
But there are other factors in play, including "more people with a variety of underlying illnesses because we do a better job of keeping people alive and functioning in our society," he said.
"When those people become sick that's when they are hospitalized because they get more severely ill," he added.
Additional information gathered on 2,393 adults who were hospitalized due to lab-confirmed flu symptoms showed that more than half -- 68% -- had at least one existing medical condition, the CDC reported. The most common conditions reported were cardiovascular disease, metabolic disorder, obesity, and chronic lung disease.
Among 223 hospitalized children the picture looks different. Slightly less than half -- 48% -- had an underlying medical condition, most commonly asthma, a neurologic disorder, or obesity.
Caused by viruses, flu is a contagious respiratory illness with mild to severe symptoms that can sometimes lead to death.
The majority of reported hospitalizations, 83.4%, were the result of type A flu virus infections and most of those were H3N2.
The CDC found that circulating flu strains this season are a mix of H3N2, H1N1 and B viruses. H3N2 strains are continuing to dominant for the seventh week of the year as they have throughout the season. H3N2 commonly leads to more severe illness and more hospitalizations, according to the CDC.
The CDC confirmed 14,715 new infections for the week ending February 10, bringing the cumulative season total to 196,673.
Among adults, the proportion of pneumonia- and flu-related deaths basically remained flat at 9.5% of all deaths reported during the week ending February 3, the CDC reported, noting that these data are always two weeks delayed. This rate is higher than the anticipated 7.4% pneumonia- or flu-related deaths estimated for the week.
"Knowing what we know about previous H3N2 seasons and looking at the data you can see a fairly steady rise of influenza B," said Nordlund. She added that "we might see a bump in activity" because of the B strains of the flu.
The CDC cautions that people who've been sick with one strain of the flu can become sick again by a different strain during the same season -- so a flu shot can still be helpful for the unvaccinated.
Earlier this week an advisory committee to the CDC recommended FluMist, the nasal spray version of the influenza vaccine, be used during the 2018-19 season.
"It's a welcome return," said Schaffner. "Pediatricians and all the kids they immunize will be glad to see it back so they won't have to endure another shot."
For the past two flu seasons, the Advisory Committee on Immunization Practices, a panel of immunization experts, has not recommended the nasal spray option based on its lackluster performance compared to the flu shot.
The company looked into this and has done research to find out why that happened, explained Schaffner. "And they think they have solved the problem," he said. "But we'll see next year."
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