Looking at the data for recent weeks, CDC spokeswoman Kristen Nordlund said, "we're still continuing to see a decline in influenza-like activity. Even though It looks like all signs point to decreasing influenza activity, we're still in what we normally think of as flu season."
Caused by viruses, flu is a contagious respiratory illness with mild to severe symptoms that can sometimes lead to death.
The CDC confirmed 6,856 new infections for the week ending March 3, bringing the season total to 230,038 since October.
The states still experiencing high activity are Alaska, Arizona, Arkansas, Georgia, Indiana, Kansas, Kentucky, Massachusetts, Michigan, Missouri, Nebraska, New Jersey, New Mexico, New York, Pennsylvania, South Carolina, South Dakota, Texas, Vermont, Virginia and Wyoming.
In addition, there was moderate flu-like illness in 15 states; the District of Columbia, Puerto Rico and 14 states experienced either low or minimal activity during the week ending March 3.
"We're certainly seeing less states with high influenza-like illness activity, and it seems like things are easing up a little bit on the East Coast and in the Midwest," Nordlund said. "There's a cluster of states in the South having high activity."
Overall, flu activity is going down, she said -- while urging caution. "If people aren't feeling well and think they might have flu, there's still a chance they could have it."
The CDC also reported five additional flu-related deaths in children, increasing the total number of pediatric deaths for the season to 119 as of March 3.
According to the report, 3.7% of people who visited their doctors complained of flu-like illness for the week ending March 3. Though that's above the expected level of 2.2% for the week, the percentage has gone down from the previous week, when the rate was 5%.
A total of 24,644 confirmed flu-related hospitalizations were reported between October 1 and March 3, according to the CDC.
The cumulative rate of flu-related hospitalizations rose to nearly 86 people out of every 100,000 in the ninth week of 2018, an uptick from about 82 out of every 100,000 last week, the surveillance report estimated.
Examining the laboratory evidence, the CDC found that circulating flu strains this season are a mix of H3N2, H1N1 and B viruses. H3N2 strains continued to be dominant as they have throughout the season, but the proportion of influenza B viruses increased for the week. H3N2 commonly leads to more severe illness and more hospitalizations, according to the CDC.
For example, the majority of hospitalizations, just over 80%, were the result of type A flu virus infections, and most of those were H3N2, during the ninth week of the year.
Among adults, the proportion of pneumonia- and flu-related deaths decreased to 8.8% of all deaths reported during the seventh week of the year, the CDC reported, noting that these data are always two weeks delayed.
In a Thursday hearing on Capitol Hill on flu preparedness before the US House Committee on Energy and Commerce, Rick Bright, director of the Biomedical Advanced Research and Development Authority, addressed the development of new flu treatments.
"We have not had a new class of antivirals for 20 years," Bright told the members, adding that the influenza virus continues to change and so can develop "high levels of resistance" against the current Food and Drug Administration-approved antiviral medicine, oseltamivir (Tamiflu). In particular, H7N9, seen primarily in China but not in the US, is most resistant, he said.
Nordlund said the CDC is not concerned about this. "We work very closely with the Chinese and the countries that border China. We monitor the situation going on there," she said.
And the numbers support the lack of concern. The CDC found 8% resistance among H1N1 influenza A virus strains against oseltamivir, but the more severe H3N2 strains showed no resistance against the popular drug.
Nordlund concluded with a recommendation for people who have not done so to get a flu shot.
"As along as flu is circulating, people should -- if they have not already -- still get their flu vaccine," she said. People most at risk of developing serious complications include the elderly, young children, pregnant women and people with underlying medical conditions. Anyone at higher risk should see their doctors if they feel ill, the CDC recommends.