The worst of the flu season is over, but increasing numbers of people are being infected with a secondary strain of the respiratory virus that could produce a late-season bump, according to a federal health report released Friday.
Public-health officials have said this flu season is likely to continue until mid-April, and the intensity of illness has made it the worst since the swine flu pandemic of 2009-10. An additional 17 child deaths were reported across the country for the week ending Feb. 24. That raises the total number of pediatric deaths to at least 114 for the 2017-18 season.
In Arkansas, 179 people, including three children, had died from the flu as of Tuesday. The flu season has been the state's most deadly since the state began tracking flu-related deaths in 2000.
The percentage of doctor visits for treatment of flu symptoms dropped for a second week in a row, according to the latest report from the federal Centers for Disease Control and Prevention. About 5 percent of all doctor visits were for treatment of fever, cough and other symptoms -- down from 6.4 percent the previous week. But flu activity is still high and widespread nationwide.
"Today's flu data show activity is down significantly for the second consecutive week, which means we peaked in early February," said CDC spokesman Kristen Nordlund. "However, this is about the same level of influenza-like illness that we saw at the peak of last season, so there is still a lot of flu out there."
Arkansas officials used a two-week analysis of emergency-room visits to conclude that they, too, believe that flu cases have peaked.
This season of fevers, chills, muscle aches and fatigue has been especially severe because of the predominant flu strain circulating. It's an influenza A virus known as H3N2, the most deadly of the two influenza A viruses and two types of influenza B viruses that are responsible for seasonal flu epidemics each year.
H3N2 is associated with more complications, hospitalizations and deaths, especially among children, people older than 65 and those with certain chronic conditions.
The latest CDC report shows that the overall proportion of influenza A viruses is declining, but the proportion of influenza B viruses is increasing.
"Like previous seasons when H3N2 was dominant in the beginning of the season, we may see a late-season bump of influenza B," Nordlund said in an email.
This season's vaccine is about 36 percent effective overall, but just 25 percent effective against the H3N2 strain, according to a midseason estimate by the CDC. The lower rate means that 1 in 4 people who get the flu shot reduces his risk of becoming sick enough to need to see a doctor.
The vaccine is 67 percent effective against the other influenza A strain, H1N1, and 42 percent effective against influenza B viruses, the CDC found. Clinicians have said it is not too late to get a flu shot because there are several more weeks left in the season. Even partial protection can help to reduce the severity of illness, and prevent hospitalizations and deaths.
In children younger than 9, the vaccine actually offers much greater protection, reducing by more than half the risk of a child becoming so sick that he will need to see a doctor. As in past winter flu seasons, about three-fourths of children who have died were not fully vaccinated, according to CDC data.
Officials have said the number of pediatric deaths could be as high as or exceed the 148 deaths from the especially severe 2014-15 season, when the same flu strain was predominant.
Flu is a contagious respiratory illness, spread by a virus. It can cause a miserable but relatively mild illness in many people, but more severe illness in others.
In a bad flu season, such as this one, the CDC estimates that influenza results in as many as 35 million illnesses, about 700,000 hospitalizations, and up to 56,000 deaths in the United States.
States are required to report individual flu deaths in children to the CDC and do so through a special influenza-associated pediatric mortality surveillance system. The number of reported flu-associated children's deaths to date probably does not include all cases because of the typical lag time for reporting nonhospital deaths.
States are not required to report individual seasonal flu cases or deaths of people older than 18 to the CDC for several reasons. Seasonal influenza is not often listed on death certificates of people who die from flu-related complications.
Many seasonal flu-related deaths take place one or two weeks after a person's initial infection, and most people who die from seasonal flu-related complications are not tested for flu, or they seek medical care when it's too late in their illness for influenza to be detected from respiratory samples, according to the CDC.
Amber Smith, a recruiter for a furniture store chain in Charlotte, N.C., said she thought she didn't have to worry about the flu after a wave of illnesses that hit her company's warehouse in January and February seemed to fade. But she started to feel sick Monday and found out she had the flu. She hadn't gotten a vaccination; her boyfriend did, and he hasn't been sick.
"I feel like my head weighs 20 pounds," said Smith, who tried to go to work Friday but was sent home after a morning meeting. "But my throat isn't as sore. I feel like the flu is running its course."
Information for this article was contributed by Lena H. Sun of The Washington Post; by Mike Stobbe of The Associated Press; and by Andy Davis of the Arkansas Democrat-Gazette.
A Section on 03/03/2018