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Parainfluenza-associated hospitalizations most common in young children
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Parainfluenza virus-associated hospitalizations occur most often among children aged 0 to 2 years, with a significant increase among children aged 1 to 2 years, according to study findings in The Journal of the Pediatric Infectious Diseases Society.
Glen R. Abedi, MPH, of the CDC’s National Center for Immunization and Respiratory Diseases, and colleagues analyzed data from the National Respiratory and Enteric Virus Surveillance System to determine seasonal parainfluenza virus (PIV) trends from July 2004 to June 2010. Respiratory hospitalizations from the Healthcare Cost and Utilization Project Nationwide Inpatient Sample were multiplied by the proportion of acute respiratory infection hospitalizations associated with PIV among children enrolled in the New Vaccine Surveillance Network. This analysis produced an estimate of the number of PIV-associated hospitalizations that occurred annually among children aged younger than 5 years in the United States from 1998 to 2010. Data represented an estimated 20% stratified sample of community hospitals in the United States, according to researchers.
There were an estimated average of 74,315 bronchiolitis hospitalizations each year, with a rate of 3.1 hospitalizations per 1,000 children. Children aged 6 to 11 months had the highest hospitalization rate: 15.3 hospitalizations per 1,000 children. An estimated 3% of bronchiolitis hospitalizations were associated with PIV, with the highest rate among children aged 1 to 2 years (6.8%). No bronchiolitis hospitalizations among children aged 3 to 4 years were associated with PIV. Researchers estimated there were 3,888 PIV-associated bronchiolitis hospitalizations annually, and most were associated with PIV-3.
There was an estimated average of 18,289 croup hospitalizations each year; with a rate of 0.9 hospitalizations per 1,000 children. More than half (55.3%) of them occurred among children aged 1 to 2 years. An estimated 46.6% of croup hospitalizations were associated with PIV (n=8,481), and 63.2% occurred in children aged 1 to 2 years. PIV-1 was the most frequent subtype, accounting for 26.3% of cases.
An estimated average of 232,774 pneumonia-related hospitalizations occurred. Children aged 0 to 5 months accounted for 50.8% of hospitalizations. PIV was associated with 5.5% of pneumonia hospitalizations, an estimated 10,186 annually. Of these, 54.4% were associated with PIV-3. Children aged 6 to 11 months had the highest number of PIV-associated pneumonia hospitalizations.
Regarding seasonality, PIV-1 occurred biennially, with circulation beginning to rise between May and July, peaking in September or October, and decreasing between December and January. PIV-3 circulated annually, rising in March and peaking between April and July. PIV-2 circulation was less defined than PIV-1 or PIV-3, but activity was greatest between August and January. PIV-4 was not reported frequently enough to establish a definite seasonal pattern.
“The results indicate that the bulk of PIV-associated hospitalizations among children aged less than 5 years occurs from ages 0 to 2 years, with a marked increase among 1- to 2-year olds. This finding suggests that immunization would be most effective in preventing hospitalizations if the vaccine were administered early in the first year of life,” the study authors wrote.
Furthermore, according to the researchers, some vaccine candidates currently in development are directed at PIV-3 alone or in combination with RSV. However, results of the current study show that PIV-1 may be the better serotype for a vaccine.
Disclosure: The researchers report no relevant financial disclosures.
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