Flu Vaccine: The Best You Can Do Is Not the Best We Can Do

As the CDC and nearly every health group on the planet will tell you, getting vaccinated against influenza is the best thing you can do to avoid getting infected, and that's still true. But if influenza can roll across the country despite a tightly-matched vaccine, how good are our existing vaccines?
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This year's precocious and somewhat ferocious flu season shows that our current vaccination approach is more feeble than we'd like to admit. According to the Centers for Disease Control (CDC), 2012-2013 is shaping up to be a highly active flu season. The party started up a little earlier than usual (most commonly, the flu peaks in February) and last Friday the CDC announced that infection rates have officially reached epidemic levels.

About 80 percent of this year's flu infections are coming from an H3N2 influenza A virus, and 20 percent are coming from an influenza B virus. Our old friend H1N1 -- the pandemic 2009 "Swine Flu" -- and a second influenza B virus claim smaller bit roles.

The good news from the CDC is that antigen characterization -- a look at the nitty-gritty molecular makeup of the viruses -- shows that three of these viruses (H3N2, B/Yamagata, and H1N1) are well-matched in this year's vaccine. The second B virus, B/Victoria, isn't in there, but it's been active in recent flu seasons and was covered by annual flu vaccinations from the 2010-11, 2011-12 flu seasons.

The bad news is that according to new CDC research released on Friday, getting vaccinated is no guarantee that this year's angel of darkness will pass you by. The CDC's most recent study showed the vaccine to be 55 percent effective against this year's major player, H3N2, and 70 percent effective against influenza B; average the two, and you get 62 percent.

The CDC describes this year's vaccine as "moderately effective," but if your kid comes home with a 62 percent, a "D," you might not describe their effort as moderately effective. Considering that the standard childhood vaccine series provide protection in the 80-90 percent or higher range, maybe that D is more like a C+ or B -.

As the CDC and nearly every health group on the planet will tell you, getting vaccinated against influenza is the best thing you can do to avoid getting infected, and that's still true. But if influenza can roll across the country despite a tightly-matched vaccine, how good are our existing vaccines? And if current vaccines aren't so good, is working harder to get them to everyone -- "universal immunization," the CDC's most recent push -- a real solution, or just a feel-good answer?

This October, the University of Minnesota's Center for Infectious Disease Research and Policy, in conjunction with an advisory group made up of 13 internationally-recognized experts, released a report titled "Comprehensive Influenza Vaccine Initiative." The report is the result of a two-year comprehensive review of the entire influenza process -- from the laboratory bench science, to the production facilities, to the ERs, hospitals and clinics.

The authors' conclusion? Flu vaccine effectiveness has been sharply overestimated, primarily because we've had a hard time knowing for certain who's been infected. Diagnosis on the basis of clinical symptoms alone is difficult because the flu, with its classic symptoms of high fever, muscle aches, sore throat and dry cough, has a lot of imitators. In the CDC study noted above, only 36 percent of the potentially flu-infected patients found by researchers ended up having laboratory-proven influenza.

Since diagnosis of influenza based on clinical symptoms alone is not accurate, we rely on lab evidence. For this recent study, the CDC used a sophisticated technique called polymerase chain reaction (PCR), but many older vaccine studies have relied on a cruder technology that measures flu antibody levels in the blood. For most people, influenza infection raises the body's flu antibody levels four-fold, but we now know that vaccination blunts that response: It's as if the immune system got to practice with the vaccine, so that when the real flu came along, it didn't have to get that worked up about it. Not understanding that vaccination blunts the typical antibody response gives the false impression that people who have been vaccinated don't get the flu, since their antibody levels are less likely to reach higher, confirmatory levels. In other words, this old technology makes the flu vaccine seem more powerful than it is.

With that in mind, the "Comprehensive Influenza Vaccine Initiative" group went through every vaccine effectiveness study available and tossed out those that were either weakly designed or couldn't rigorously tell who really had the flu. Instead, they relied only on strong studies that used either the PCR technology or actually grew the virus in culture from the afflicted's "snot-sicle."

Trivalent inactivated vaccine (TIV) makes up about 90 percent of the vaccine doled out each year. What the research group found was that over a combined 12 flu seasons, TIV was 59 percent effective at preventing the flu, but its performance was somewhat erratic. In a couple of seasons it was 75 percent effective, but there were some studies for some years that found it to only be 16 percent or 22 percent effective. Unfortunately, that data was on healthy adults; the authors found no randomized controlled trials for TIV that met their stricter criteria in evaluating vaccine effectiveness for adults older than 65, or for young children -- the two groups that are most susceptible to a serious bout of influenza. Live-attenuated flu vaccine, the nasal spray vaccine, was 83 percent protective in children aged 6 months to 7 years, but evidence of benefit for other ages, including adults and seniors, was limited or lacking altogether.

"Fifty-nine percent effective" for TIV was quite a bit below what had been the white coat, party line number of 70-90 percent, and the group took a little flak for raining on the parade of the CDC, who has been vigorously recommending universal vaccination since 2010. On an individual or even group basis, it's a completely legitimate argument: Sixty percent effective or 70 percent effective, flu vaccination is still a good idea -- it spares some people what can be a miserable illness, and better yet, it saves some lives.

But the "Comprehensive Influenza Vaccination Initiative" wanted to look at the big picture, and they didn't like what they saw. They found that our overestimation of the current flu vaccine's potency has evoked a confidence and complacency that's kept us from pushing on to something new, to what they termed "game-changing" innovation in influenza vaccine development and production.

"We found a general perception that we don't need a better flu vaccine, we just need to make more of it faster," noted the study's lead author, Dr. Michael Osterholm. He's quick to point out that there's a lot of exciting research going on in influenza vaccination, some of it quite promising, but without a sense of urgency or need, it's hard to raise intellectual or financial capital.

"It takes about a billion dollars to bring a new vaccine to market," Osterholm lamented. "Our group talked with all kinds of investors who said, 'Why would we invest that kind of money to develop a new vaccine, when all we're hearing is this one works -- we just need to figure out how to get it to everyone?'"

Vaccination might still be the best thing one can do, but is 62 percent the best that we can do? The flu virus is always changing and adapting; we should be too.

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