Medically attended pediatric influenza during the resurgence of the Victoria lineage of influenza B virus

SummaryObjectivesDuring the 2002–2003 season, a new variant of influenza B co-circulated with influenza A viruses. This study examines the characteristics and outcomes of children with influenza A and B virus infection vs. other acute respiratory illnesses.MethodsA retrospective chart review was performed on children with laboratory-confirmed influenza infection, and influenza negative acute respiratory illnesses that prompted a hospital visit.ResultsChildren with influenza were more often previously healthy and presenting with upper respiratory symptoms, while influenza negative patients typically had underlying medical conditions, and lower respiratory tract disease. Children with influenza B were older, were more likely to be in school, and presented with myositis more frequently than those with influenza A. A third of children with influenza A, and 42% with influenza B required hospitalization. The highest hospitalization rates were in infants under one year. No healthy children, and only 15% of those with chronic medical problems, had received influenza vaccine. Vaccine efficacy was estimated to be 82.6%.ConclusionsMost children with influenza were previously healthy. Overall, a third of children with influenza required hospitalization. Influenza A and B were clinically indistinguishable, except for older age and higher incidence of myositis in patients with influenza B. Influenza vaccine coverage in both healthy and high-risk children was low

Neonatal CD8 T-cell Hierarchy Is Distinct from Adults and Is Influenced by Intrinsic T cell Properties in Respiratory Syncytial Virus Infected Mice

Following respiratory syncytial virus infection of adult CB6F1 hybrid mice, a predictable CD8+ T cell epitope hierarchy is established with a strongly dominant response to a Kd-restricted peptide (SYIGSINNI) from the M2 protein. The response to KdM282-90 is ∼5-fold higher than the response to a subdominant epitope from the M protein (NAITNAKII, DbM187-195). After infection of neonatal mice, a distinctly different epitope hierarchy emerges with codominant responses to KdM282-90 and DbM187-195. Adoptive transfer of naïve CD8+ T cells from adults into congenic neonates prior to infection indicates that intrinsic CD8+ T cell factors contribute to age-related differences in hierarchy. Epitope-specific precursor frequency differs between adults and neonates and influences, but does not predict the hierarchy following infection. Additionally, dominance of KdM282-90 –specific cells does not correlate with TdT activity. Epitope-specific Vβ repertoire usage is more restricted and functional avidity is lower in neonatal mice. The neonatal pattern of codominance changes after infection at 10 days of age, and rapidly shifts to the adult pattern of extreme KdM282- 90 -dominance. Thus, the functional properties of T cells are selectively modified by developmental factors in an epitope-specific and age-dependent manner

Influenza surveillance in an urban area

In Houston the yearly influenza epidemics have been defined virologically by community surveillance obtained by testing specimens submitted from patients with acute respiratory illnesses seen by sentinel physicians. Mortality attributed to influenza and pneumonia has increased regularly during the period of intense influenza virus activity, but the peak has lagged two weeks behind the peak of activity defined by the virological surveillance. Most of the deaths occurred in persons aged 65 years and older; the average annual rate has been 103.5 per 100,000 in that age group. Hospitalizations for pneumonia and other acute respiratory conditions also peaked during influenza epidemics; the highest rate occurred in the elderly, but children under five years of age also had high rates. Morbidity in the ambulatory setting was highest in children. The average visit rate for children under five years of age was 28%; the rate decreased to about 10% for persons aged 10 years and older. Improved coverage with more immunogenic vaccines is needed to protect the elderly. Young children would benefit from universal immunization with available live attenuated vaccines