We're on the Verge of the Deadliest Flu Season in History
Another year, another flu season. Each flu season brings a different main strain of the virus. And this year's, the influenza A virus known as H3N2, is supposed to be among the worst.
How bad? Worse than the 2009 swine flu. So bad that 215,000 people are already sick. So bad that cases in states like Arizona are up more than 758 percent over the same time last year.
The Centers for Disease Control and Prevention report that the strain is widespread in 46 states, including the densely populated California, New York, Massachusetts and Virginia. And as if this couldn't sound any more like a horror movie, a virus mutation means that this year's flu vaccine has proved to not be very effective at all- only ten percent of cases in Australia have responded to the vaccine, The New England Journal of Medicine reports.
Five to 20 percent of the U.S. population contracts the flu each year, and somewhere between 3,000 and 49,000 Americans die from flu-related illness, the CDC. With H3N2 out in the air, it's likely that the number of deaths will fall on the higher end of the spectrum this year. There have 36 deaths by the flu in Los Angeles County, compared to 17 last year.
Though it initially earned the inauspicious name of "Aussie Flu", H3N2 is now being called "The Hospitalizer" by the press.
For the first time ever, a cell-grown H3N2 vaccine reference virus was used to produce the H3N2 component of a cell-based vaccine called Flucelvax. The remaining Flucelvax vaccines were manufactured using egg-grown reference viruses.
It's those egg-grown references that are causing the mutations, though, according to Scott Hensley, PhD, associate professor of microbiology in the Perelman School of Medicine at the University of Pennsylvania. "Our experiments suggest that influenza virus antigens grown in systems other than eggs are more likely to elicit protective antibody responses against H3N2 viruses that are currently circulating," he said in a press release. "The 2017 vaccine that people are getting now has the same H3N2 strain as the 2016 vaccine, so this could be another difficult year if this season is dominated by H3N2 viruses again."
Most influenza vaccine antigens are prepared in chicken eggs, he goes on to explain. The problem is that mutations usually develop in the hemagglutinin protein of these eggs. In a proposed solution, the most recent edition of the influenza vaccine included a new version of H3N2 with a different outer layer protein. Even with that new outer layer, though, these vaccines are only effective against approximately 43 percent of H3N2 infections.