This year’s flu season is one of the worst in recent memory. Federal officials reported last week that this season has already caused the most hospitalizations in nearly a decade. During the week of February 10th, an additional 22 children’s deaths from the flu were reported, bringing the total to at least 84 nationwide. However, the week of February 10th was also the first week of the season in which the number of people seeking care for flu symptoms did not increase, potentially indicating that this harsh flu season may be levelling off. However, it’s far from over. Here’s what you need to know as flu season continues.
What makes this flu season so particularly bad?
This year flu season started early, and the entire county is experiencing widespread and intense flu activity. The predominant strain this year is also the nastiest – H3N2. It causes the worst outbreaks of two influenza A viruses and two influenza B viruses. The H3N2 strain is associated with more deaths, more hospitalizations, and more illnesses. It hits the very young, the elderly, and people with certain chronic health conditions particularly hard. The H3N2 strain has been around for more than 50 years and is able to change more rapidly than other flu viruses to get around the human body’s immune system.
Why are flu vaccines not as effective as other vaccines?
Before manufacturing of the flu vaccine begins in any given year, health officials must choose what strains to target long before flu season starts, without knowing for sure which strains might be prevalent. When flu vaccines are well-matched to circulating viruses, effectiveness is, at best, sixty percent. In general, flu vaccines tend to work better against influenza B and influenza A (H1N1) viruses and offer lower protection against influenza A (H3N2) viruses.
Regardless, the CDC recommends a yearly flu vaccine for everyone six months of age and older. Last year, a study in Pediatrics showed that the flu vaccine lowered the risk of flu-associated deaths by half among children with underlying high-risk medical conditions and by nearly two-thirds among healthy children.
How effective is this year's vaccine?
A CDC report released at mid-season found that the overall effectiveness rate of the vaccine is 36 percent, but it is only 25% effective against the dominant H3N2 strain, confirming what experts have suspected for some time: exceptionally bad flu seasons are dominated by the H3N2 strain, making the vaccine less effective. However, the current vaccine is 67% effective against the other influenza A strain, H1N1, and 42% effective against influenza B viruses. Also, in children under the age of 9, the current vaccine offers much greater protection, reducing the risk of becoming so sick that they need to see a doctor by half.
How long will this flu season last, and when will it peak?
Usually, flu activity peaks between December and February, with activity lasting as late as May. Experts aren’t sure when this season will peak. Even if flu activity peaks soon, there will be many more weeks of flu activity based on other seasons that were dominated by the H3N2 strain. It’s not too late to get a flu shot!
Why are so many otherwise healthy children dying from flu?
Children are particularly vulnerable this season, but as in past flu seasons, three quarters of the children who have died have not been fully vaccinated. One reason why even healthy children are more vulnerable than adults to the flu has to do with the way their immune system responds. If they haven’t received a flu shot, infection with a flu strain the immune system has not previously seen can cause an overreaction, leading to widespread and ultimately fatal inflammation.
What flu symptoms should parents watch for in their children?
Bring your child to the doctor if he or she isn’t drinking, is overly lethargic, has chest pain in a specific place, or is having difficulty breathing. If he or she has been improving but then gets suddenly worse, they need to be seen right away - this could be a sign of a secondary bacterial infection. Don’t delay - “These kids don't do well when brought in late for care,” according to Patsy Stinchfield, a pediatric nurse practitioner and senior director of infection prevention and control at Children's Hospitals and Clinics of Minnesota.
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For more information on symptoms and treatment of the flu, check out our Integrity First Aid Handbook – The Flu.