Why you should get a flu shot this year

As leaf piles on the front lawn anticipate the salted sidewalks of winter, so marquees fronting every Walgreens, Rite-Aid and CVS advising us of their friendly vaccination services presage the onset of yet another flu season. For most of us, getting the flu means a miserable few days to a week of coughing, sore throats, runny noses, chills, body aches and draining fatigue. But it can be much more than that. According to the Centers for Disease Control and Prevention, influenza viruses kill between 12,000 and 56,000 Americans each year, with up to 710,000 made ill enough to require hospitalization. Those numbers include not only people who forgot or refused vaccination, but many who did get their flu shot and got sick anyway. In fact, according to Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, the vaccine produced for the 2016-17 flu season protected just 42 percent of those who received it. If you're not covered by some form of health insurance, the going price for the pleasure of a shot in the arm will typically run you $20-$40 or more; and even if your cost is covered, what's the point if it's all just a crap shoot? Well, it is a gamble; in fact, in some years the vaccine's effectiveness has been as low as 10 percent. But professional gamblers account for what's at stake as well as the odds for success. Consider these additional numbers from the CDC for last year's flu season: Even though the vaccine was only deemed 42 percent effective, it nonetheless prevented 5.1 million cases of influenza, prevented 71,000 hospitalizations, saved 2,900 lives and boosted the U.S. economy some $5.8 billion by improving worker vitality on the job and reducing days taken off for illness. Take-home message: Get your shot. In fact, the CDC recommends everyone over the age of 6 months be vaccinated each year (unless they have a known allergy to an ingredient in the vaccine). But why each year? The measles, mumps and rubella vaccine is 97-percent effective and is not repeated after two early childhood doses. What's different about influenza? The strains of the measles, mumps and rubella viruses that are circulating today are little different from the versions I encountered as a boy 60 years ago. Once vaccinated against them, a person's immune system knows what to expect and will destroy the viruses whenever they are encountered again. In one way, it's no different with influenza. If you got your flu shot in 2016, your immune system will forever remain on guard against that 2016 strain of virus. But things get a tad complex now, so hold on. … There are three categories of influenza viruses: A, B and C. All three can be mild or very nasty, but types B and C only affect humans and have never caused epidemics, while type A also can infect various birds and mammals and has been responsible for all influenza epidemics. Our immune system recognizes a virus as a foreign body to be destroyed by proteins found on its outer surface. But influenza viruses have a work-around for that. They are surrounded by a membrane that is studded with two types of proteins, rather like two flavors of Tootsie pops attached to the membrane by their sticks. The proteins are called hemagglutinin and neuraminidase — just remember H and N proteins and we're good. There are 16 known versions of H proteins and nine types of N proteins. Scientists label a given strain by which H and N proteins they have. For instance, the so-called Spanish flu that killed more than 670,000 Americans in the 1918-19 worldwide pandemic was caused by the H1N1 strain. H1N1 also was the cause of the "swine flu" epidemic of 2009-10 that killed more than 17,000, while the "bird flu" epidemic of 1997 that resulted in the death of 359 humans and the slaughter of many million domestic fowl was caused by the H5N1 strain. For the most part, it's the influenza virus's H proteins that our immune systems learn to recognize. However, the viral genes that determine the chemical makeup of an H protein mutate at a quick clip (especially for type A viruses) and therein lies the problem. Last year's and this year's vaccines were designed to protect against three flu viruses: a type A H1N5, a type A H3N2 and a type B virus. But last year's shot won't offer the same level of protection as this year's vaccine because this year's H proteins are slightly different than last year's — enough so that they won't ring alarm bells in our immune systems. Of course, the pharmaceutical industry has a golden goose here; it really is important to get the new version of a flu shot every year. However, recall my comment above on the long-term effectiveness of the MMR vaccine. A number of research groups report they are hot on the trail of a "one-and-done" vaccine for all forms of influenza virus. Now wouldn't that just shovel your driveway? Ken Baker is a scientist and a retired biology professor. If you have a natural history topic you'd like the author to consider for an upcoming column, email your idea to rweaver@advertiser-tribune.com.