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Flu Routs Vaccine During Rough 2018-19 Season

Our best defense against influenza needs better stopping power against the scariest name in the flu game: H3N2.

That’s the unanimous verdict of health experts after the flu vaccine had another rough season fighting off the flu. The vaccine was incompletely ineffective against the powerful H3N2 strain that dominated the end of the 2018-19 flu season, offering an alarming zero percent protection, according to the U.S. Centers for Disease Control and Prevention. That left the vaccine’s overall protection rate for the season at a poor 29 percent.

Every team has a season they’d like to forget. The designers of this year’s vaccine would like to forget this terrible influenza season and restart building the vaccine from scratch.

“The flu vaccine turned out to be a big disappointment again,” Associated Press Medical Writer Mike Stobbe said.

The upside: Despite its lower-than-normal effectiveness, the CDC estimates the vaccine prevented up to 90,000 hospitalizations. The vaccine also delivered strong protection against H1N1 and offered adequate flu protection to 49 percent of children 6 months to 8 years old.

However, the vaccine protected just 12 percent of people age 65 and older, according to CDC statistics.

In an effectiveness study of 4,128 people, CDC scientists evaluated the differences in the incidence of flu between vaccinated and unvaccinated people to gauge the flu vaccine effectiveness (VE) overall, against each flu strain and among various groups.  The CDC bases vaccine effectiveness on preventing cases bad enough to send someone to the doctor.

The vaccine’s inability to do anything but punt against H3N2 this season is especially concerning.

There was no “significant protection” against that strain, the CDC’s Brendan Flannery said.

After two bad seasons of flu ineffectiveness, the vaccine is bound to come under even greater scrutiny.  The World Health Organization designs the vaccine annually to protect against three or four prevalent influenza strains. The ingredients are based on predictions of what strains will make people sick the following winter.

Vaccine designers again guessed wrong this year, leading to the vaccine’s lowest effectiveness rate over the last 10 years since the winter of 2014-15, in which the vaccine successfully repelled influenza in a mere 19 percent of cases.

The FDA’s Vaccines and Related Biological Products Committee (VRBPAC) and the WHO have studied H3N2’s late-season surge and took longer to develop next season’s vaccine.

The DNA of next year’s shot has been designed to be able to stand up to and repel the troublesome strain.

“H3N2 viruses have presented an increasing challenge to vaccine virus selection due to frequent changes in the H3N2 viruses,” the CDC reported.

Next year’s vaccine will include two new influenza A strains in the trivalent and quadrivalent vaccines.

Trivalent vaccines will include:

  • Influenza A/Kansas/14/2017 (H3N2-like virus)
  • Influenza A (A/Brisbane/02/2018 (H1N1)pdm09-like virus
  • Influenza B (Colorado/06/2017-like Victoria Lineage virus

Quadrivalent vaccines will also include a second lineage of the Influenza B virus: B/Phuket/3073/2013-like (Yamagata lineage) virus.

Despite its limitations and losses this season, the flu vaccine remains a remarkably effective defense for millions of Americans during the sickliest time of the year. The WHO is betting a better vaccine game plan can help next season’s vaccine have a comeback season.

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