So far this flu season, there have been 9.7 million cases, 87,000 hospitalizations and 4,800 deaths, including 32 children. Of these, 21 were associated with the influenza B virus, which experts say is more severe in children and young adults.
In previous seasons, the influenza B virus didn’t circulate until the end of the season, but for the first time since 1992 to 1993, the virus represents more than 59 percent of cases. During the past two seasons, influenza B accounted for less than 10 percent of sicknesses.
As a result, this year’s vaccine “is not a very good match for B,” said Anthony Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, CNN reports. “It’s not an awful match, but it’s not a very good match.”
According to recent Centers for Disease Control and Prevention data, this year’s flu shot is a 58 percent match for B/Victoria. This means that it will 58 prevent of influenza B cases. In the remaining 42 percent, it could prevent the individual, especially children, from developing serious complications.
The Washington Post reports that epidemiologists are still investigating the mismatch as a possible cause of the increased rate of pediatric deaths. More children have died at this stage in the season than any previous one (since the CDC began collecting pediatric death data in 2004). What’s more, CDC officials caution that the virus may not have hit its peak yet.
What Can Providers Do?
Even with the likely mismatch, the CDC stresses that the best way for patients to protect themselves against the flu is to get vaccinated. Remind them that the shot always responds to four strains of the virus, and it will still reduce severity of illness in people infected with the unexpected influenza B subgroup.
Providers should also remind patients of standard preventive behaviors:
- Wash your hands often. This is more effective than hand sanitizer.
- Avoid contact with sick people.
- If you start to experience symptoms, especially if you’re around sick people, call your provider and ask for a prophylactic antiviral, such as Tamiflu. Note that these only work if you use them within the first 72 hours of exposure.
Early Season Pediatric Influenza B/Victoria Virus Infections Associated with a Recently Emerged Virus Subclade — Louisiana, 2019, Centers for Disease Control and Prevention.
Weekly U.S. Influenza Surveillance Report, Centers for Disease Control and Prevention.