Immunization Update

2021, January/February Adirondac

WITH ALL THE ATTENTION focused on the COVID-19 vaccine, folks may forget the host of very effective vaccines available already against other illnesses. This is unfortunate, in that vaccines (along with clean drinking water and fluoridation) are the most effective public health measures we currently have. I will focus on the backcountry traveler, but hit upon other important vaccines.

These comments address only North American travel; trekkers headed to other global regions should consult with a travel medicine expert.

The number one immunization question I get from individuals about to embark on a long trek is, “Do I need a tetanus shot?” The quick answer is, When was your last one?”

Tetanus is, fortunately, an extremely rare disease in the U>S> today (I have seen one case in a career spanning four decades). However, it is also an absolutely horrible, generally fatal, affliction. It is cause by a microorganism generally found in soil, usually when a would is deeply contaminated. The nature of wilderness trekking is such that tetanus-prone injuries are most unusual.

The tetanus vaccine is extremely effective. After the initial series of shots, a tetanus “booster” is recommended for adults every ten years, although some experts advise another booster after a tetanus-prone injury if five years have elapsed.

Today, tetanus immunization for adults should be combined with diphtheria and pertussis (TDaP0. While diphtheria is about as rare as tetanus, pertussis (“whooping cough”) is quite common. In small infants, it cause severe respiratory illness, resulting in several fatalities in the U.S. every year. In adults, it generally causes an upper respiratory infection with a severe, prolonged cough. One of the reasons for adults to maintain pertussis immunization is to avoid transmission to infants. Indeed, the importance of adult TDaP booster may be more for protection from pertussis than tetanus.

In terms of importance for wilderness traveler, I consider annual influenza (“flu”) immunization number one. Influenza is a nasty virus, with the clever ability t change its properties often enough that a vaccine which is effective this year is likely useless next year. This is why we need to repat our influenza vaccination annually. How effective the vaccine is in any particular year depends upon how successfully scientists predict the specific strains that will be circulating. (Epidemiology trivia: Before he became “distracted” by COVID-19, Dr. Anthony Fauci was deeply involved in the development of the “holy grail” of immunization: an influenza vaccine that would be effective against all strains of the virus.)

The next vaccine is one that may surprise readers. Hepatitis A (Hep A) is a virus that causes a form of liver inflammation that spreads quite easily within groups. Like most intestinal infections, it is spread by the hand-to-mouth route, or occasionally in water. Most Hep A infections in the U.S. today occur in small clusters. There have been several reports of such clusters among campers, although this has generally been in developed campsites rather than the wilderness. Hepatitis A vaccine is highly effective. It can be combined with a vaccine for hepatitis B, a more severe form of liver inflammation spread by contact with blood or other body fluids. Hepatitis B vaccine has been part of the routine childhood immunization series for many years.

Two other vaccines are strongly recommended for adults, although not specifically for wilderness travel. The pneumococcus vaccine (sometimes imprecisely referred to as “pneumonia” vaccine) protects against a variety of severe bacterial infections that are frequent causes of death in adults. And the shingles vaccine protects against a very painful condition associated with reactivation of childhood chickenpox.

Where should we get our shots? Ideally, we should all have a “medical home” with a primary care provider who can oversee all of our preventive care. From a practical standpoint, however, many pharmacies have better supplies of vaccines, much better hours, and access to up-to-date vaccine recommendations.

Tom Welch, M.D., is a physician at Upstate Medical University in Syracuse, and a member of the Wilderness Medical Society. He is a licensed professional guide and a Wilderness Education Association instructor, and has guided groups in the Adirondacks, Montana, and Alaska. More information is available on his website and blog, Jana Shaw, M.D., M.S., a national authority in immunization practice at the State University of New York (SUNY), reviewed this column and provided helpful suggestions.


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Topics: Disease, Readiness, Vaccines