Medicine For People!

October 2015

Schematic of Influenza Vaccine Creation
"Reassortment" by MouagipThis vector graphics image was created with Adobe Illustrator. - File:Reassortment HiRes.jpg (Link Studio for NIAID). Licensed under Public Domain via Commons.

Choices of Flu Vaccine

Contents

  • Influenza Vaccine: Make Your Choice
    • Influenza and Immunization
    • How to Choose an Influenza Vaccine
    • High-Dose Influenza Vaccine
    • Type B influenza
    • Quadrivalent Influenza Vaccine
    • Preservative-Free Vaccine
  • October Schedule

Influenza and Immunization

Type A influenza kills many more people than it gets credit for. If you are a healthcare worker, you take the vaccination to protect your patients, and if you aren't, you may choose the immunization to protect yourself or your relatives, or as insurance that you don't miss significant work from a case of the "hard flu."

From our previous newsletters, you know the simple observations that led to the practice of immunization, observations made some 500 years ago and still true today. You are aware that the benefits of immunization are similar to those of brushing and flossing your teeth. They are invisible unless you try to go without the preventive measure.

Of course, nothing is perfect, not least the process of immunization, so we will close this series of newsletters we began last winter with a critical review of influenza vaccine marketing and economics.

How to Choose an Influenza Vaccine

There are several choices now of different influenza vaccines. You may choose a nasal mist or an injected vaccine. You may choose a narrower or a wider spectrum of protection, or you may choose on the basis of cost. As an example, some years ago we pointed out that the cost of the shingles vaccine exceeded its value for many people.

Let's take a critical look now at different forms of influenza vaccine.

High-Dose Influenza Vaccine

Influenza vaccine is produced in two strengths. The standard potency works best in people under the age of 65; over that age, the new high-dose version reduces the incidence of type A influenza by about 25% compared to the standard vaccine. The high-dose version costs about twice as much as the standard version. At about $50-$60 per dose this may sound in like a good deal. But let's look a little more closely at the numbers published in the New England Journal of Medicine.

These researchers vaccinated over 31,000 people against type A influenza: some 15,000 people with the standard dose and another 15,000 with the high dose. To help you understand the numbers, I have included a column of 15,000 people who were not vaccinated. Attack rates for influenza vary from year to year and place to place, and can be as high as 10% in the worst years. That said, authorities accept 4% as an average rate, which means that 15,000 unvaccinated people could expect about 600 cases of type A influenza per year.

This table shows the results of the study.

Annual Cases of Influenza

No Vaccine Standard Dose High Dose
Number of people 15,000 15,000 15,000
Number of people who came down with influenza 600 240 180

The writers of this article divided 240 by 180 and reported, accurately, that when compared to the standard dose, the high-dose vaccine reduced the number of cases of influenza by about 25%. Looking at the table above, you can see that it would be just as accurate to say that the high-dose vaccine prevented 60 cases of influenza among the 15,000 people immunized. That number doesn't sound so exciting, does it? This means over 200 people would have to substitute the high dose for the standard dose to prevent one case of influenza.

If the high-dose vaccine cost no more than the standard vaccine, you would of course wish to have it. If cost is not a consideration for you, certainly you should choose it. But the economics are underwhelming when compared with the standard vaccine.

This may explain why the nation's contagious illness watchdog, the Centers for Disease Control, does not recommend the high-dose vaccine over the standard influenza vaccine. It does, as I do, strongly advise that the most important thing is getting the immunization itself.

Type B influenza

Of the two major types of influenza, we have an easier time immunizing against type B because it circulates only in humans. That means it doesn't take a detour through poultry or swine which can cause unexpected changes that can lead to worldwide deadly epidemics. In general, type B virus causes a less severe illness than type A, but given a susceptible person, type B can kill just as well.

Quadrivalent Influenza Vaccine

Most vaccines protect against more than one type of flu. This year's standard-dose vaccine, the quadrivalent (four-pronged) vaccine, protects us against:

  • Type A influenza virus (A/California/7/2009 (H1N1)pdm09-like virus)
  • Type A influenza virus (A/Switzerland/9715293/2013 (H3N2)-like virus)
  • Type B influenza virus (B/Phuket/3073/2013-like)
  • Type B influenza virus (B/Brisbane/60/2008-like)

These are the only two type B strains and they mutate slowly enough that this vaccine ensures you will be protected from type B influenza. The type A strains are more of a moving target; the strains listed above appear to be the leading threats. No one expects that any influenza vaccine made with current technologies will offer much more than 50% protection when averaged over several flu seasons. Still, it is certainly worth cutting your risk of this serious illness in half!

Preservative-Free Vaccine

Vaccines usually contain a form of mercury preservative called thimerosal. The actual amount is tiny, but there has been increasing concern about the effects of even miniscule amounts of this heavy metal on the body. Our office has offered preservative-free vaccines for years. This fall we are giving a preservative-free quadrivalent vaccine for $40. We can only order this in the spring, and we now have a limited and dwindling supply.

Nonetheless, the standard vaccine is still much better than nothing, and I personally would take it if it were the only choice. The risk of influenza out-weighs the risk of any vaccine now approved and available.

October Schedule

We will be closed the week of October 19.

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Medicine for People! is published by Douwe Rienstra, MD at Port Townsend, Washington.