Children Offered Intranasal Influenza Vaccine
Children Offered Intranasal Influenza Vaccine
By Pat McGinley, FNP, MSN
Summary-The Centers for Disease Control and Prevention recommends 15 immunization injections for children by age 6. With the controversy related to the use of oral vs. injectable polio vaccine, this number may go even higher. The addition of an elective injection such as influenza vaccine is unlikely to have popular appeal. Children ages 0-4 are at highest risk for contracting influenza. They often spread the illness to adults and endanger elderly grandparents and others at high risk. Researchers offer hope for a more acceptable route of administration in a new intranasal influenza vaccine.
· The intranasal vaccine was 89-94% effective in one- or two-dose regimens.
· Vaccinated children had fewer febrile illnesses.
· Vaccinated children had 30% fewer occurrences of febrile otitis media.
The Centers for Disease Control and Prevention's (CDC) 1998 immunization schedule for children recommends no less than 15 injections from birth to age 6.1 (See Recommended Childhood Immunization Schedule, inserted in this issue.) With the number of immunizations required for preschool and school entrance, an elective injection such as the influenza vaccine is unlikely to gain popularity. However, one of the highest rates for influenza is in youngsters aged 0-4 years with subsequent spread to adults, including elderly grandparents and others at high risk for complications associated with influenza.2 (See Table 1, p. 26.)
Table 1
Est. Rates of Influenza-Associated Hospitalization Per 100,000 Population
Population Group by Age |
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(All 65+ considered high risk) |
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Source: Centers for Disease Control and Prevention. Prevention and Control of Influenza. Recommendations of the Advisory Committee on Immunization Practices. MMWR Recommendations and Reports - Preview. Morbidity and Mortality Weekly Report 1998; 47(RR-06).
Table 2
Vaccines, Toxoids Recommended for Adults By Age Groups, United States
Vaccine/Toxoid |
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Influenza |
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Pneumococcal |
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Measles |
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Mumps |
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Rubella |
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Varicella |
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Td1 |
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1. Td = Tetanus and diphtheria toxoids, adsorbed (for adult use), which is a combined preparation containing <2 flocculation units of diphtheria toxoid.
2. One dose for all persons born in 1957 or later, two doses for health care workers, college students, and travelers born in 1957 or later.
3. Those born after 1956.
Source: Centers for Disease Control and Prevention, Atlanta. For more details, visit http://www.cdc.gov/nip/adult.htm. Information about use, administration, and cautions for influenza vaccine also is available at this site.
In response to these issues and the high incidence of influenza in the pediatric population with subsequent spread to other populations, researchers have developed and tested the efficacy of an intranasal influenza vaccine for use in children. The vaccineefficacy was 93%, and even more remarkable, researchers found that influenza resulted in otitis media in more than 20% of the placebo group but in less than 1% of the vaccine group. The authors concluded that preventing influenza in young children would decrease the incidence of otitis media, a common ailment in children.
Results of a prospective, randomized, placebo controlled, multicenter clinical study to determine the efficacy of the intranasal live attenuated, cold-adapted, trivalent influenza virus vaccine were reported in The New England Journal of Medicine.3 Researchers administered 0.5 ml intranasal vaccine into each nostril of more than 1,500 healthy children ages 15-71 months during the 1996-1997 influenza season. The intranasal vaccine contained strains from influenza type A (HIN1), A (H3N2), and B (Harbin) subtypes.
Two doses of vaccine or placebo were given approximately 60 days apart to 1,314 children, while 288 received only one dose of vaccine or placebo.3 Vaccine or placebo was administered using a spray applicator calibrated to deliver two 0.25 ml aliquots (one per nostril) in an aerosolized spray. Total vaccine or placebo volume was 0.50 ml.
Two centers used primarily a one-dose regimen vs. a two-dose regimen. The study found both regimens effective: one-dose 89% and two-dose 94%. Both centers switched to the one-dose regimen later in the vaccination season. Researchers monitored subjects by telephoning parents at regular intervals throughout the influenza season to inquire about signs and symptoms of influenza in the children. Presence of symptoms warranted a visit to the provider for viral cultures within four days after the onset of the illness.
Vaccine Easy to Administer, Well-Tolerated
Researchers reported the vaccine was well-tolerated, easily administered, and had no serious adverse effects. The vaccine was significantly efficacious in the development of antibody seropositivity to influenza viruses in all age groups.
Ninety-two percent of the vaccinated children converted seropositive to influenza A (H3N2) after the first dose. After the second dose, 96% of the study subjects developed antibodies to influenza A (H3N2) and B subtypes, and 61% had antibodies to influenza (H1N1).
The placebo group had an 18% rate of culture-positive influenza, while those who received intranasal influenza vaccine had only 1% of culture-positive influenza. Influenza in the vaccinated group was much milder and shorter when compared with the placebo group.
More than half of the study subjects had at least one sibling. The authors evaluated the vaccine's ability to reduce spread of influenza within a household and found that a vaccinated child within the family did not reduce the incidence of influenza among siblings. The authors conclude that to reduce the transmission of influenza among children, the vaccine must be administered to a widespread cohort at a young age.
Implications for Practice
In addition to educating parents about the importance of influenza vaccination in young children, teach them to recognize the difference between symptoms of flu and those of the common cold. (See patient education handouts in English and Spanish, inserted in this issue.)
The idea of a new non-injectable method of administering vaccines to children subjected to multiple injectable vaccinations during their first six years appeals to parents, children, and clinicians alike. Clinical research showing it is practical and effective makes one consider the possibility of intranasal administration for other vaccinations. It might ease the pain and fear generated by injections and result in better compliance with immunization schedules.
Compliance with CDC recommendations has been less than optimal since the inception of vaccines and is a concern for health care professionals. Many believe a major reason for noncompliance is multiple injections. Parents complain the child is a pincushion, and clinicians sorrow with the child who must receive several injections at a single visit. With many immunizations required for preschool and school entrance, an elective injection such as influenza vaccine is not readily acceptable to parents, children, or health care providers.4
There are other concerns as well: If the intranasal form of influenza vaccine is more expensive than the injectable form, as new pharmaceuticals often are, cost may contribute to poor acceptance. Nasal spray is inarguably less painful than injection, but children still may find it unpleasant and be fearful enough to resist its administration and require the same physical restraint needed for injections. Such resistance and restraint often results in copious tears. Does the effect of crying that induces nasal secretions have any effect on the amount of vaccine absorbed in the nasal mucosa?
I hope these issues will be addressed in subsequent research involving intranasal administration of vaccines and other medications in the pediatric population.
References
1. Centers for Disease Control and Prevention. Recommended childhood immunization schedule United States, January-December 1998. Pediatr Ann 1998;27:339-348.
2. Centers for Disease Control and Prevention. Preven tion and Control of Influenza. Recommen dations of the Advisory Committee on Immunization Practices. MMWR Recommendations and Reports - Preview. Morbidity and Mortality Weekly Report 1998;47(RR-06).
3. Belshe R, Mendelman P, Treanor J, et al. The efficacy of live attenuated, cold-adapted, trivalent, intranasal influenza virus vaccine in children. New Engl J Med 1998;338:1405-1412.
4. Reis E, Jacobson R, Tarbell S, Weniger B. Taking the sting out of shots: control of vaccination-associated pain and adverse reactions. Pediatr Ann 1998;27: 375-385.
Recommended Reading
· Glezen WP, Taber L, Frank A, et al. Influenza virus infections in infants. Pediatr Infect Dis J 1998;16: 1065-1068.
· Rodewald L. Childhood vaccination successes, yes, but the job is not finished. Pediatr Ann 1998;27: 335-336.
· Udovic S and Lieu T. Evidence on office-based interventions to improve childhood immunization delivery. Pediatr Ann 1998;27:355-361.
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