Barnstable County Report

Don’t Let Fears Of H1N1 Keep You From Getting That Regular Flu Shot

By George Heufelder, MS, RS, Director,
Barnstable County Department of Health & Environment

The newsprint on the recent occurrence of the H1N1 “swine flu” virus is barely dry as we now begin preparations for the next influenza season. No, it’s not quite time to pencil in the flu clinic date, but it is never too early to get a good baseline understanding of the influenza issue. That’s because the 2009 flu season will be complicated by the recent run of H1N1 novel virus (swine flu).

First a few basics. Although the recent H1N1 class of virus is new, that class of virus is common in pigs and has been observed since1930. In fact, 51 percent of pigs in the north-central United States have shown antibody evidence of infection with swine H1N1 and there already are vaccines for pigs to help contain the spread of certain influenza strains among pigs as well as by contact to humans.

When a virus enters cells it basically instructs them to assemble viruses to resemble the invader. The “manufacturing” part of the cell does just that until it can do no more. The cell then degrades, releasing the newly-formed viruses to seek out more cells to repeat the process. The real problems occur when pigs or other animals contract more than one type of virus at the same time. During this co-infection period, a genetic “swap shop” can occur, where gene segments from these viruses trade segments with each other. The resulting mutation not only creates a unique new “signature,” but also may take on the different traits, such as transmissibility and persistence.

Today’s new H1N1 virus actually is believed to be the result of a combination of two viruses that normally circulate in pigs in Europe and Asia, plus an avian (bird), and a human virus. This is called a quadruple reassortment.

Normally, immune systems can recognize familiar invading viruses by certain characteristics. Thus, when we receive a vaccine, we are actually giving our body a preview of a potential invader so our immune system can ramp up to manufacture a defense when a real infection occurs. However, a novel virus, like the recent H1N1 swine flu, has changed its signature so much that the body’s defense system can’t “read” it and may not respond in time to avoid the outcome of illness and possibly death.

What does all this have to do with the coming flu season?  Well, each year, the influenza vaccine is manufactured for the next season, based on the best guess at which viruses will be in circulation. The vaccine is trivalent, meaning three strains of viruses are used. Although this year’s cocktail includes an H1N1 attenuated virus strain, it is not the strain that recently circumnavigated the globe and caused all that concern.

Therefore, the Centers for Disease Control of the United States be;ieves that vaccination for seasonal flu this year will not impart protection against the novel H1N1!

The timing of the outbreak was such that this novel virus could not be manufactured in quantity for inclusion in the trivalent seasonal flu vaccine.

But this does not mean you can skip your annual flu shot!  Remember, over 36,000 Americans die and over 200,000 are hospitalized annually from seasonal influenza. Get that seasonal flu shot as you have in past years since these flu viruses will also be in circulation. If the novel H1N1 strain returns along with the seasonal influenza, there may be a need for additional vaccinations. And I say “vaccinations” because any new vaccine for the newest H1N1 may well involve more than one dose.

Also, don’t forget all the standard precautions reported in our last issue. Hand washing and covering coughs, among other measures, are very effective in preventing even this newest virus. And keep abreast of developments so, when the time comes, you can make informed decisions on vaccination options