Flu season has peaked, but late bump may loom

  • FILE - In this Feb. 7, 2018 file photo, a nurse prepares a flu shot at the Salvation Army in Atlanta. The nation’s nasty flu season has been fading for two weeks now, and health officials now feel confident the worst is over. The Centers for Disease Control and Prevention said the season apparently peaked in early February, when 1 of every 13 visits to the doctor were for fever, cough and other symptoms of the flu. That intensity level was among the highest seen in a decade. But CDC officials on Friday, March 2, said it's been falling since then, and last week dropped to 1 in 20. (AP Photo/David Goldman, File) David Goldman

Washington Post
Friday, March 02, 2018

The worst of the flu season is over, but increasing numbers of people are being infected by a secondary strain of the respiratory virus that could lead to 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 2009-2010. An additional 17 child deaths were reported across the country for the week ending Feb. 24. That brings the total to at least 114 for the 2017-2018 season.

The percentage of doctor visits for flu symptoms dropped for a second week in a row, according to the latest indicators from the Centers for Disease Control and Prevention. About 5 percent of all doctor visits were for 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 spokeswoman 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.”

This season of misery, fevers, chills, muscle aches and overwhelming 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 report shows 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, a mark that falls to 25 percent against the H3N2 strain, according to a midseason estimate by the CDC. The lower rate means that one in four people who get the shot reduce their risk of becoming sick enough to need to see a doctor.

In addition, 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.