Flu Vaccine Recommendations for Children

Just recently, the Centers for Disease Control (CDC) expanded its influenza (flu) vaccination recommendation to include children between the ages of six months and 18 years. So, with the exception of infants under the age of 6 months, the recommendation for flu vaccination is approaching one of becoming universal.

Why has this occurred, and what is the relevance for persons who love the outdoors? To answer the first question, I think that we now have an increasing appreciation about the enormous benefits and minimal risks associated with the vaccine(s), and for just how devastating a case of influenza can become. Here is some information about the flu:

The influenza viruses are responsible for seasonal epidemics of the flu, a predominantly respiratory disease. In temperate climates, influenza is a cold weather disease. The illness is recognized by sudden high fever, sore throat, cough, headache, muscle aches, weakness, and occasional (more common in children) nausea with vomiting and/or diarrhea. Influenza is distinguished from a common cold by its intensity, particularly of the headache and muscle aches. The virus is transmitted from person to person via virus-laden large droplets (greater than 5 microns in diameter) generated when infected persons cough or sneeze. “Stomach flu” is a misnomer, because it is not caused by influenza virus, but rather, by other viruses and bacteria.

Elderly or infirm individuals are at greatest risk for becoming severely debilitated or developing complications, such as pneumonia, from influenza. General therapy for the flu is the same as that for a common cold: rest, adequate nutrition, increased fluid intake, and medicine for fever. Vaccines are prepared each year that are somewhat effective in the prevention of types A and B influenza. Oseltamivir phosphate (Tamiflu) is a drug that is used for treatment of influenza types A and B in adults who have been ill for no more than 2 days. It is given in an adult oral dose of 75 milligrams (mg) twice daily for 5 days. The pediatric dose is based on age and weight. For a child age 1 to 12 years: weight less than 15 kilograms (one kilogram equals 2.2 pounds), 30 mg twice daily for 5 days; 15 to 23 kg, 45 mg twice daily for 5 days; 23 to 40 kg, 60 mg twice daily for 5 days; weight greater than 40 kg or age greater than 12 years, 75 mg twice daily for 5 days. An alternative is zanamivir (Relenza) 10 mg inhaled twice a day for 5 days for all ages.

During an epidemic, victims may benefit from the administration of the oral drug rimantadine 200 mg by mouth daily for 5 to 7 days in adults, and 5 mg per kg of body weight per day (up to 150 mg) for 5 to 7 days in children. An alternative is amantadine in a dose of 100 mg twice daily for 5 days in adults, or 2.2 mg per kg of body weight (up to 75 mg) twice daily for 5 days in children. These are available by prescription for the prevention and treatment of type A influenza (they are ineffective against type B). They are associated with several toxic effects and also contribute to emergence of resistance against them by the influenza virus type A.

Avian influenza A (H5N1, which exists in at least 8 subgroups, or “clades”) may be resistant to the adamantane drugs (rimantidine and amantadine), so would be treated with zanamivir or oseltamivir, the former in a dose of 75 mg and the latter in a dose of 150 mg by mouth twice a day for 10 days. This form of influenza is carried and spread by birds, notably poultry and perhaps wild birds. It has been found in other species, such as cats, tigers, leopards, pigs, ferrets, rabbits, rats, and emus, from where it might more rapidly mutate to a form more infectious to humans. Avian flu has a very aggressive profile, with a high (up to 60%) overall mortality rate in human victims. Infected humans show “typical” flu symptoms, followed rapidly by respiratory and multi-organ failure. There is little evidence for mild or asymptomatic human infections. With regard to protective masks, an N95 respirator mask is supposed to have at least a 95% filtration capability at filtering a 0.3 micron droplet, which carries the virus, but not the virus particles individually.

Flu vaccination is being advocated for virtually all children also because recent evidence suggests that children are often flu spreaders. If you have children in school or day care, or who congregate in groups, such as for athletics, you know that this is true. Although most of the people who die from influenza are elders over the age of 65, it is still anticipated that controlling the spread of the disease in the pediatric population will be quite important.

It has been reported that there are no anticipated shortages of flu vaccine for this flu season (2008-2009). If you are in a high risk group (elder, young child, or person with chronic illness), your doctor will almost certainly recommend that you be vaccinated. Since it is impossible to predict when and where the disease will strike, the sooner you receive your immunization, the better.

Influenza vaccine is administered in one or two injections to children and adults in October and November (in the Northern Hemisphere) prior to the flu season (December through March), with a maximum duration of effect of 6 months. Persons 3 years of age or older should receive a single intramuscular injection of 0.5 ml. Children 6 to 35 months of age should receive only 0.25 ml. Children younger than 9 years of age who have never been immunized should receive two doses spaced at least 4 weeks apart.

Persons for whom annual vaccination is especially recommended include:

1. all persons who wish to reduce the risk of becoming ill with influenza or transmitting the disease to others

2. children ages 6 months to 18 years, particularly those receiving long term aspirin therapy who might be at risk for experiencing Reye syndrome

3. all persons ages 50 years or greater

4. women who will be pregnant during influenza season

5. adults and children who have immunosuppression caused by medications or HIV

6. adults and children who have chronic pulmonary (including asthma), cardiovascular (except hypertension), kidney, liver, blood, or metabolic (including diabetes) disorders

7. adults and children with any condition that might compromise respiratory function

8. healthcare personnel

Each year, the vaccine contains the influenza virus strains that are felt to be most prevalent in the United States. Inactivated (killed-virus) influenza vaccine should not be given to those who are sensitive to egg products. “Whole” vaccines should not be given to children under the age of 13 years. Children should be given “split” vaccines, which have been chemically treated to reduce adverse reactions.

A live, attenuated nasal spray vaccine (FluMist) is at least as effective as injected vaccine, and is approved for persons ages 5 to 49 years who are free of chronic illnesses. It is administered as a spray of 0.25 ml into each nostril (0.5 ml total dose). Children ages 5 to 8 years old who have not been previously immunized should receive two doses spaced at least 6 weeks apart. FluMist should not be administered to family members or close contacts of immunosuppressed persons requiring a protected environment.

Amantadine hydrochloride (Symmetrel) and rimantadine are prescription oral drugs that interfere with viral uncoating within living cells and are moderately effective in preventing influenza A. However, because they confer no protection against influenza B, they are not considered substitutes for appropriate immunization.

To answer the second question, it is important to be immunized against influenza because the disease is "a hammer." If you are engaging in outdoor sports, exploration, or other activities, and you are stricken with the flu, you will potentially become seriously ill. In the past, I had the misfortune to spend a winter week in the mountains with the worst headache and muscle aches of my life, a non-immunized victim of influenza. Since then, I would personally much rather have a sore arm (if that...) for a day than run the risk of being taken down for the count by this powerful illness.

image courtesy of Centers for Disease Control

Tags: influenza, flu vaccine, immunization, wilderness medicine, outdoor medicine, healthline

Labels: flu, flu vaccine, immunization, influenza, vaccination

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