Influenza immunization: overlooked information for the non-health profession person

August is, among other things, National Immunization Awareness month. In light of that fact, your Intrepid Pharmacist, who is also a nationally certified immunizer and trainer, will be spending the next couple of columns on this unusually controversial topic. This week: seasonal influenza.

The coming flu season is likely to be one that will be remembered, what with two different strains of influenza circulating adversely affecting two different populations. The flu vaccine has come a long way in the public consciousness since the turn of the century. General public apathy towards the “flu shot” underwent a metamorphosis in 2003 when four children in Colorado died of influenza complications within days of each other. The general media’s penchant for sensationalism actually did public health a favor by creating such a panic that for the first time in recent memory, people were actually demanding their flu shots. Since then, our influenza vaccination rate, especially among the susceptible age groups (elderly and children) has seen a steady increase. In 2003, there were 152 pediatric deaths from influenza compared with only 56 in the 2008 season.
 

Before addressing the H1N1 (or swine flu) that will add to the turbulence of this season, we should consider a few often misunderstood and unexplained points about seasonal influenza and its vaccine. The general media rarely comments on these points because a) it is not a sensationalizable panic-inducing headline and b) much of this information, while fairly easy to follow, is dry. You will want to have a canteen with you while you read it, lest you begin to see mirages in the distance that are not your screen saver kicking in. Ah, the thirst for knowledge!

First, the biggest challenge with any form of influenza is the incubation and contagion time. A person with influenza is sick with it up to 24 hours before he or she knows it. So, in that lag time between acquiring the flu and becoming sick with it, a person has up to a full day to share with his or her friends. He (or she) also has up to five days after symptoms develop to speard the flu.

Second, the seasonal flu is in a state of constant flux. Mutations (changes) to the virus’ outer coating of hemagglutinin and neuraminidase (which is what the H and the N in all flu listings refers to) make it impossible to have a vaccine that can cover all possible forms. Just as it is impossible to have a lottery ticket with all possible winning combinations. If you want to know more about those details, click here and here, but fill your canteen first; you’ll need it! The resulting vaccine is science’s best guess as to what flu strains will be prevalent in any given season since the vaccine has to be grown and manufactured months ahead of the actual season.

These two points come together to create the problem and Rule that is point three: even if the health gurus get it right, international travel can ruin it overnight. All it takes is one person visiting or returning to the United States from some other part of the globe who is unaware he is sick with and carrying a version of influenza not covered in that year’s vaccine. As soon as he lands (always in major cities like New York, Atlanta, or Los Angeles) he can begin infecting anyone with whom he comes into contact via coughing, sneezing, or shaking his unwashed hand that just covered his mouth when he coughed. (See, there is something to be said for the fist-bump greeting!) This scenario alone should give the reader a great appreciation for the task facing Public Health globally speaking. And this is on top of the virus’ natural tendency towards mutation.

The easy spread factor also helps contribute to several Flu Fables, such as the widely held belief that getting a flu vaccine causes the flu. In reality, the influenza in the injected vaccine (including Fluvirin, Fluzone and Afluria) has been inactivated using heat or formaldehyde. (Your Intrepid Pharmacist knows what you are thinking and no, any formaldehyde in a vaccine is at far lower exposure levels than formaldehyde levels from cigarettes, automobile tailpipe emissions, pressed wood furniture products or even in the air (0.03 parts per million) you breathe). When the killed virus is extracted and placed into the vaccine, the components are inactive, but the virus shell (those H’s and N’s) remains intact and recognizable to the immune system. This allows the receiver to gain immunity without the discomfort of actually having to get sick first. Likewise, the newer live attenuated nasal spray version (FluMist) is very temperature sensitive and the molecule falls apart once it reaches the heat of the throat area and beyond, making it impossible to get the flu from this vaccine as well.

Two factors play a role in the flu-from-flu-shot-fable. First, vaccines are not instant gratification, creating a constant source of confusion to the Microwave Generation. The vaccine takes a good 14 days to become effective; immune response does not happen overnight. Encountering someone already sick with influenza before that window has passed will likely result in the flu, as will encountering someone carrying a strain not covered in that year’s vaccine.

So why all the fuss over a vaccine that can be hit or miss? Short answer: minimizing spread and mortality (e.g. death) and the high costs of hospitalization that goes with it. The real danger of influenza is the mortality rate. Though it is unlikely to ever see the death numbers of the famed 1918 flu that killed some 50 million people worldwide, death from influenza still happens every year. It is just not hyped in the general media. The final totals come out well after the season over and by then spring is here and summer looming, so who cares about flu deaths by then? The flu season is over; no fear or panic to induce, and thus no ratings share gains to be had. This may sound cynical, but if the news media is to be the information source it markets itself to be, then this kind of information should be relevant no matter when the statistics come out.

The general media does do something right in that it routinely states in its flu info sound bytes the two biggest targets of the vaccine are the elderly and children. Here is the why that is never included: While both of these groups are at higher risk of death, the elderly especially, it is school age children who are the primary infection source. The highest spread source is via children, not adults, including the elderly. One study even found that the more kids in a population the greater number of flu and respiratory illness cases seen among the adults. In fact, the elderly have an infection rate comparable to the regular adult population. However, the elderly comprise the overwhelming majority in the death department. For these reasons, those two age groups are primary vaccine targets.

Alongside the seasonal influenza this year, we have the H1N1 version, which carries with it a higher mortality rate and a different susceptibility profile. It is also a different vaccine. And then there are those pseudo-factual anti-vaccine websites that will also be addressed, dressed down and their factual flaws exposed. We will save that for next time, however, since several readers are looking parched, and their canteens are empty.