Safety of cold-adapted live attenuated influenza vaccine in a large cohort of children and adolescents

Trivalent Intranasal Influenza Vaccine, Live

OBJECTIVE

To review human data on the efficacy, safety, and clinical use of trivalent intranasal influenza vaccine, live (TIIVL).

DATA SOURCES

A MEDLINE search (1966–3rd week of January 2004) using the terms influenza vaccine, intranasal administration, and FluMist was conducted. References from pertinent articles were also reviewed.

STUDY SELECTION AND DATA EXTRACTION

Studies conducted in humans and published in English were selected. Double-blind, controlled trials evaluating the efficacy and safety of TIIVL were evaluated.

DATA SYNTHESIS

Administration of TIIVL results in mucosal and humoral immunity to influenza. Results of clinical trials in children and adults have demonstrated that TIIVL reduces the incidence of influenza. In children, TIIVL was also associated with a decrease in febrile illness and febrile otitis media. In adults, reductions in workday absences and medical visits due to febrile upper respiratory tract illness were also documented. TIIVL is well tolerated, with rhinorrhea or nasal congestion and sore throat occurring more frequently than with placebo.

CONCLUSIONS

TIIVL is an alternative to intramuscular inactivated influenza vaccine in healthy individuals between 5 and 49 years of age. However, the vaccine is contraindicated in the majority of patient populations for whom annual influenza vaccination is recommended. THIS ARTICLE IS APPROVED FOR CONTINUING EDUCATION CREDIT ACPE UNIVERSAL PROGRAM NUMBER: 407-000-04-037-H01

Safety, Efficacy, and Effectiveness of Live, Attenuated, Cold‐Adapted Influenza Vaccine in an Indicated Population Aged 5–49 Years

BACKGROUND

Three important studies have supported licensure of live, attenuated, cold-adapted influenza vaccine (CAIV-T [FluMist; MedImmune Vaccines]): (1) a pediatric efficacy trial involving children 15-71 months of age, (2) a large safety study of medically attended events occurring among children 1-17 years of age, and (3) an effectiveness trial involving healthy working adults 18-64 years of age.

METHODS

During the United States Food and Drug Administration (FDA) review for the approval of CAIV-T for use in healthy persons, additional subgroup analyses were conducted to evaluate the safety, efficacy, and effectiveness of the vaccine, by use of various age subsets not prespecified by the original protocols. CAIV-T is currently approved by the FDA for use in healthy persons 5-49 years of age. In this article, we present data from some of the aforementioned subanalyses.

RESULTS

The efficacy of CAIV-T in children >or=5 years of age (age range of the children in year 1 of the study, 60-71 months; age range of the children in year 2 of the study, 60-83 months) was similar to that reported for the entire cohort in year 1 (90.6%; 95% confidence interval [CI], 70.3%-97.1%). In year 2 of the study, efficacy was 86.9% (95% CI, 70.8%-94.1%), despite the presence of antigenically drifted influenza type A/Sydney/5/97 (H3N2), which caused most illnesses that occurred in year 2. Safety outcomes for children 5-17 years of age revealed no significant difference between vaccine recipients and placebo recipients, with regard to acute respiratory events, acute gastrointestinal events, systemic bacterial infection, or rare events possibly related to influenza. Effectiveness among adults 18-49 years of age was similar to that reported for the entire cohort--for example, for occurrence of severe febrile illness, there was a 19.5% reduction (P=.02) in adults.

CONCLUSIONS

The present reanalysis summarizes data on the indicated uses for CAIV-T in the indicated population aged 5-49 years.

Immunizations, neonatal jaundice, and animal-induced injuries

PURPOSE OF REVIEW

Published studies during the past year about three topics important to the pediatric clinician-- immunizations, neonatal jaundice, and animal-induced injuries-are concisely reviewed.

RECENT FINDINGS

Recent updates regarding vaccines including the questionable link with autism, implementation of universal influenza vaccination for young children, the efficacy of pneumococcal vaccine against invasive disease, and new information on pertussis, varicella, hepatitis A, hepatitis B, measles, and rotavirus vaccination are discussed. No association between measles/mumps/rubella vaccine or thimerosal-containing pertussis vaccine and autism is evident. Universal influenza vaccination for children 6 to 23 months of age will be recommended for the 2004-2005 flu season, and this implementation should reduce significant school absenteeism as well as complications seen last year including encephalopathy, seizures, respiratory failure, and pneumonia. Pneumococcal vaccine significantly reduces rates of invasive pneumococcal vaccine in healthy and HIV-infected children, although it does not appear to greatly affect otitis media rates. A reduction in post-vaccine febrile seizures appears to be present since the introduction of acellular pertussis vaccine. Multiple outbreaks in varicella have been reported since the introduction of the varicella vaccine, and a booster vaccination may be necessary in the future. Methods for detecting and preventing severe neonatal hyperbilirubinemia are reviewed, as well as anticipated recommendations from the American Academy of Pediatrics for the detection and management of hyperbilirubinemia. High bilirubin levels in preterm infants may result in hearing dysfunction and developmental impairment. The American Academy of Pediatrics has recommended a higher level of monitoring for newborn jaundice and treatment of hyperbilirubinemia in an effort to prevent kernicterus and sequelae from elevated bilirubin levels, including post-discharge follow-up appointment by day 3 to 5 of age. Dog bites in children with resultant post-traumatic stress disorder, rabies, and salmonellosis from pet reptiles in the home are also addressed. Clinicians need to be aware of the risk for rabies bites, need to recognize that dog bites in children appear to cause post-traumatic stress disorder in more than half of cases, and need to know how to educate patients on how to prevent salmonellosis from pet reptiles and amphibians.

SUMMARY

Progress has been made in immunizations, especially immunization for influenza, pneumonia, and pertussis. It is recommended that monitoring for neonatal hyperbilirubinemia be more thorough to prevent the consequences of this condition. Rabies, post-traumatic stress disorder from dog bites, and salmonellosis associated with pet reptiles constitute an important area for patient education.

New vaccines for old diseases: trivalent cold-adapted influenza vaccine

Schoolchildren regularly have the highest influenza attack rates. Schoolchildren also are accessible for vaccination; school-based vaccine clinics can facilitate delivery of vaccine to a high proportion of children in a short period of time. CAIV-T has advantages for immunization of this group due to the effectiveness of a single dose, ease of administration, and ready acceptance by children. Modeling of control for an influenza epidemic by Longini et al. has shown vaccination of 70% of school children would dampen epidemics and significantly reduce the exposure of vulnerable people in the community. The goal of the central Texas trial is to demonstrate this effect in the field. Universal childhood immunization could be an important supplement to current control efforts. Vaccine coverage with TIV has leveled off since 1997; no progress toward the Healthy People 2010 goals of 90% coverage has been made after 4 years in the new decade. The number of excess deaths is expected to double within the next 25 years if control methods are not intensified. CAIV-T may become an important adjunct to control measures and can facilitate influenza pandemic preparedness.