BACKGROUND Community-acquired pneumonia is a leading infectious cause of hospitalization and death among U.S. adults. Incidence estimates of pneumonia confirmed radio-graphically and with the use of current laboratory diagnostic tests are needed. METHODS We conducted active population-based surveillance for community-acquired pneumonia requiring hospitalization among adults 18 years of age or older in five hospitals in Chicago and Nashville. Patients with recent hospitalization or severe immunosuppression were excluded. Blood, urine, and respiratory specimens were systematically collected for culture, serologic testing, antigen detection, and molecular diagnostic testing. Study radiologists independently reviewed chest radiographs. We calculated population-based incidence rates of community-acquired pneumonia requiring hospitalization according to age and pathogen. RESULTS From January 2010 through June 2012, we enrolled 2488 of 3634 eligible adults (68%). Among 2320 adults with radiographic evidence of pneumonia (93%), the median age of the patients was 57 years (interquartile range, 46 to 71); 498 patients (21%) required intensive care, and 52 (2%) died. Among 2259 patients who had radio-graphic evidence of pneumonia and specimens available for both bacterial and viral testing, a pathogen was detected in 853 (38%): one or more viruses in 530 (23%), bacteria in 247 (11%), bacterial and viral pathogens in 59 (3%), and a fungal or mycobacterial pathogen in 17 (1%). The most common pathogens were human rhinovirus (in 9% of patients), influenza virus (in 6%), and Streptococcus pneumoniae (in 5%). The annual incidence of pneumonia was 24.8 cases (95% confidence interval, 23.5 to 26.1) per 10,000 adults, with the highest rates among adults 65 to 79 years of age (63.0 cases per 10,000 adults) and those 80 years of age or older (164.3 cases per 10,000 adults). For each pathogen, the incidence increased with age. CONCLUSIONS The incidence of community-acquired pneumonia requiring hospitalization was highest among the oldest adults. Despite current diagnostic tests, no pathogen was detected in the majority of patients. Respiratory viruses were detected more frequently than bacteria. (Funded by the Influenza Division of the National Center for Immunizations and Respiratory Diseases.)

Background The primary role of respiratory syncytial virus (RSV) in causing infant hospitalizations is well recognized, but the total burden of RSV infection among young children remains poorly defined. Methods We conducted prospective, population-based surveillance of acute respiratory infections among children under 5 years of age in three U.S. counties. We enrolled hospitalized children from 2000 through 2004 and children presenting as outpatients in emergency departments and pediatric offices from 2002 through 2004. RSV was detected by culture and reverse-transcriptase polymerase chain reaction. Clinical information was obtained from parents and medical records. We calculated population-based rates of hospitalization associated with RSV infection and estimated the rates of RSV-associated outpatient visits. Results Among 5067 children enrolled in the study, 919 (18%) had RSV infections. Overall, RSV was associated with 20% of hospitalizations, 18% of emergency department visits, and 15% of office visits for acute respiratory infections from November through April. Average annual hospitalization rates were 17 per 1000 children under 6 months of age and 3 per 1000 children under 5 years of age. Most of the children had no coexisting illnesses. Only prematurity and a young age were independent risk factors for hospitalization. Estimated rates of RSV-associated office visits among children under 5 years of age were three times those in emergency departments. Outpatients had moderately severe RSV-associated illness, but few of the illnesses (3%) were diagnosed as being caused by RSV. Conclusions RSV infection is associated with substantial morbidity in U.S. children in both inpatient and outpatient settings. Most children with RSV infection were previously healthy, suggesting that control strategies targeting only high-risk children will have a limited effect on the total disease burden of RSV infection.

Background U.S. incidence estimates of pediatric community-acquired pneumonia hospitalizations based on prospective data collection are limited. Updated estimates with radiographic confirmation and current laboratory diagnostics are needed. Methods We conducted active population-based surveillance for community-acquired pneumonia requiring hospitalization among children <18 years in three hospitals in Memphis, Nashville, and Salt Lake City. We excluded children with recent hospitalization and severe immunosuppression. Blood and respiratory specimens were systematically collected for pathogen detection by multiple modalities. Chest radiographs were independently reviewed by study radiologists. We calculated population-based incidence rates of community-acquired pneumonia hospitalizations, overall and by age and pathogen. Results From January 2010-June 2012, we enrolled 2638 (69%) of 3803 eligible children; 2358 (89%) had radiographic pneumonia. Median age was 2 years (interquartile range 1-6); 497 (21%) children required intensive care, and three (<1%) died. Among 2222 children with radiographic pneumonia and specimens available for both bacterial and viral testing, a viral and/or bacterial pathogen was detected in 1802 (81%); ≥1 virus in 1472 (66%), bacteria in 175 (8%), and bacterial-viral co-detection in 155 (7%). Annual pneumonia incidence was 15.7/10,000 children [95% confidence interval (CI) 14.9-16.5], with highest rates among children <2 years [62.2/10,000 (CI 57.6-67.1)]. Respiratory syncytial virus (37% vs. 8%), adenovirus (15% vs. 3%), and human metapneumovirus (15% vs. 8%) were more commonly detected in children <5 years compared with older children; Mycoplasma pneumoniae (19% vs. 3%) was more common in children ≥5 years. Conclusions Pediatric community-acquired pneumonia hospitalization burden was highest among the very young, with respiratory viruses most commonly detected.

Among young children, outpatient visits associated with influenza were 10 to 250 times as common as hospitalizations. Few influenza infections were recognized clinically.

WHAT'S KNOWN ON THIS SUBJECT: Respiratory syncytial virus (RSV) infection is a leading cause of hospitalization among infants. Most estimates of RSV hospitalization rates are imprecise, having been calculated by using retrospective discharge diagnosis data and stratified age groups no narrower than 6 to 12 months.WHAT THIS STUDY ADDS: Prospective, population-based surveillance data for infants hospitalized with laboratoryconfirmed RSV infection were combined with birth certificate information to yield more precise age-specific hospitalization rates. These data should help determine priorities for the use of existing and future RSV prophylaxis strategies. abstract BACKGROUND: Respiratory syncytial virus (RSV) infection is a leading cause of hospitalization among infants. However, estimates of the RSV hospitalization burden have varied, and precision has been limited by the use of age strata grouped in blocks of 6 to $12 months. METHODS:We analyzed data from a 5-year, prospective, population-based surveillance for young children who were hospitalized with laboratoryconfirmed (reverse-transcriptase polymerase chain reaction) RSV acute respiratory illness (ARI) during October through March 2000-2005. The total population at risk was stratified by month of age by birth certificate information to yield hospitalization rates.RESULTS: There were 559 (26%) RSV-infected children among the 2149 enrolled children hospitalized with ARI (85% of all eligible children with ARI). The average RSV hospitalization rate was 5.2 per 1000 children ,24 months old. The highest age-specific rate was in infants 1 month old (25.9 per 1000 children). Infants #2 months of age, who comprised 44% of RSV-hospitalized children, had a hospitalization rate of 17.9 per 1000 children. Most children (79%) were previously healthy. Very preterm infants (,30 weeks' gestation) accounted for only 3% of RSV cases but had RSV hospitalization rates 3 times that of term infants.CONCLUSIONS: Young infants, especially those who were 1 month old, were at greatest risk of RSV hospitalization. Four-fifths of RSVhospitalized infants were previously healthy. To substantially reduce the burden of RSV hospitalizations, effective general preventive strategies will be required for all young infants, not just those with risk factors. Pediatrics 2013;132:e341-e348 AUTHORS:

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Background The introduction of 7-valent pneumococcal conjugate vaccine (PCV7) into the US childhood immunization schedule in 2000 has substantially reduced vaccine-serotype invasive pneumococcal disease (IPD) in both young children and unvaccinated older children and adults. All-cause pneumonia hospitalizations also markedly declined in young children by 2004. Because of concern about increases in disease caused by non-vaccine serotypes, we assessed whether the pneumonia reduction in young children was sustained through 2009 and whether pneumonia hospitalizations in older age groups also declined. Methods Annual all-cause pneumonia hospitalization rates were estimated using the Nationwide Inpatient Sample. Pneumonia hospitalizations were defined by pneumonia listed first or listed in another position if sepsis, meningitis or empyema was the first listed diagnosis. Average annual rates in pre-PCV7 (1997–1999) and late PCV7 years (2007–2009) were used to estimate annual declines in pneumonia hospitalizations. Results Annual pneumonia hospitalization rates declined by 551.1 (95% confidence interval 445.1–657.1) per 100,000 children aged <2 years, translating to 47,172 fewer hospitalizations annually compared to expected based on pre-PCV7 rates. The decline of 1300.8 (984.0–1617.6) pneumonia hospitalizations per 100,000 adults aged ≥85 years translated to 73,243 fewer hospitalizations annually. Pneumonia hospitalizations declined by 8.4 (0.6–16.2), 85.3 (7.0–163.6), and 359.8 (199.6–520.0) per 100,000 adults aged 18–39, 65–74 and 75–84 years, respectively. Overall, we estimated an age-adjusted annual reduction of 54.8 (41.1–68.5) per 100,000 or 168,182 fewer pneumonia hospitalizations annually. Conclusions Declines in childhood pneumonia were sustained during the decade since PCV7 introduction. Substantial reductions in pneumonia hospitalizations in adults were also observed.