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Persons with HIV (PWH) are at increased risk for bacterial infections, and previous publications document an increased risk for invasive meningococcal disease (IMD) in particular. This analysis provides evidence that PWH face a 6-fold increase in risk for IMD based on Active Bacterial Core surveillance data collected during 2009-2019.

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BACKGROUND: Influenza burden varies across seasons, partly due to differences in circulating influenza virus types or subtypes. Using data from the US population-based surveillance system, Influenza Hospitalization Surveillance Network (FluSurv-NET), we aimed to assess the severity of influenza-associated outcomes in individuals hospitalised with laboratory-confirmed influenza virus infections during the 2010-11 to 2018-19 influenza seasons. METHODS: To evaluate the association between influenza virus type or subtype causing the infection (influenza A H3N2, A H1N1pdm09, and B viruses) and in-hospital severity outcomes (intensive care unit [ICU] admission, use of mechanical ventilation or extracorporeal membrane oxygenation [ECMO], and death), we used FluSurv-NET to capture data for laboratory-confirmed influenza-associated hospitalisations from the 2010-11 to 2018-19 influenza seasons for individuals of all ages living in select counties in 13 US states. All individuals had to have an influenza virus test within 14 days before or during their hospital stay and an admission date between Oct 1 and April 30 of an influenza season. Exclusion criteria were individuals who did not have a complete chart review; cases from sites that contributed data for three or fewer seasons; hospital-onset cases; cases with unidentified influenza type; cases of multiple influenza virus type or subtype co-infection; or individuals younger than 6 months and ineligible for the influenza vaccine. Logistic regression models adjusted for influenza season, influenza vaccination status, age, and FluSurv-NET site compared odds of in-hospital severity by virus type or subtype. When missing, influenza A subtypes were imputed using chained equations of known subtypes by season. FINDINGS: Data for 122 941 individuals hospitalised with influenza were captured in FluSurv-NET from the 2010-11 to 2018-19 seasons; after exclusions were applied, 107 941 individuals remained and underwent influenza A virus imputation when missing A subtype (43·4%). After imputation, data for 104 969 remained and were included in the final analytic sample. Averaging across imputed datasets, 57·7% (weighted percentage) had influenza A H3N2, 24·6% had influenza A H1N1pdm09, and 17·7% had influenza B virus infections; 16·7% required ICU admission, 6·5% received mechanical ventilation or ECMO, and 3·0% died (95% CIs had a range of less than 0·1% and are not displayed). Individuals with A H1N1pdm09 had higher odds of in-hospital severe outcomes than those with A H3N2: adjusted odds ratios (ORs) for A H1N1pdm09 versus A H3N2 were 1·42 (95% CI 1·32-1·52) for ICU admission; 1·79 (1·60-2·00) for mechanical ventilation or ECMO use; and 1·25 (1·07-1·46) for death. The adjusted ORs for individuals infected with influenza B versus influenza A H3N2 were 1·06 (95% CI 1·01-1·12) for ICU admission, 1·14 (1·05-1·24) for mechanical ventilation or ECMO use, and 1·18 (1·07-1·31) for death. INTERPRETATION: Despite a higher burden of hospitalisations with influenza A H3N2, we found an increased likelihood of in-hospital severe outcomes in individuals hospitalised with influenza A H1N1pdm09 or influenza B virus. Thus, it is important for individuals to receive an annual influenza vaccine and for health-care providers to provide early antiviral treatment for patients with suspected influenza who are at increased risk of severe outcomes, not only when there is high influenza A H3N2 virus circulation but also when influenza A H1N1pdm09 and influenza B viruses are circulating. FUNDING: The US Centers for Disease Control and Prevention.

As of March 31, 2023, more than 30,000 monkeypox (mpox) cases had been reported in the United States in an outbreak that has disproportionately affected gay, bisexual, and other men who have sex with men (MSM) and transgender persons (1). JYNNEOS vaccine (Modified Vaccinia Ankara vaccine, Bavarian Nordic) was approved by the Food and Drug Administration (FDA) in 2019 for the prevention of smallpox and mpox via subcutaneous injection as a 2-dose series (0.5 mL per dose, administered 4 weeks apart) (2). To expand vaccine access, an Emergency Use Authorization was issued by FDA on August 9, 2022, for dose-sparing intradermal injection of JYNNEOS as a 2-dose series (0.1 mL per dose, administered 4 weeks apart) (3). Vaccination was available to persons with known or presumed exposure to a person with mpox (postexposure prophylaxis [PEP]), as well as persons at increased risk for mpox or who might benefit from vaccination (preexposure mpox prophylaxis [PrEP]) (4). Because information on JYNNEOS vaccine effectiveness (VE) is limited, a matched case-control study was conducted in 12 U.S. jurisdictions,† including nine Emerging Infections Program sites and three Epidemiology and Laboratory Capacity sites,§ to evaluate VE against mpox among MSM and transgender adults aged 18-49 years. During August 19, 2022-March 31, 2023, a total of 309 case-patients were matched to 608 control patients. Adjusted VE was 75.2% (95% CI = 61.2% to 84.2%) for partial vaccination (1 dose) and 85.9% (95% CI = 73.8% to 92.4%) for full vaccination (2 doses). Adjusted VE for full vaccination by subcutaneous, intradermal, and heterologous routes of administration was 88.9% (95% CI = 56.0% to 97.2%), 80.3% (95% CI = 22.9% to 95.0%), and 86.9% (95% CI = 69.1% to 94.5%), respectively. Adjusted VE for full vaccination among immunocompromised participants was 70.2% (95% CI = -37.9% to 93.6%) and among immunocompetent participants was 87.8% (95% CI = 57.5% to 96.5%). JYNNEOS is effective at reducing the risk for mpox. Because duration of protection of 1 versus 2 doses remains unknown, persons at increased risk for mpox exposure should receive the 2-dose series as recommended by the Advisory Committee on Immunization Practices (ACIP),¶ regardless of administration route or immunocompromise status.

BACKGROUND: Descriptions of changes in invasive bacterial disease (IBD) epidemiology during the coronavirus disease 2019 (COVID-19) pandemic in the United States are limited. METHODS: We investigated changes in the incidence of IBD due to Streptococcus pneumoniae, Haemophilus influenzae, group A Streptococcus (GAS), and group B Streptococcus (GBS). We defined the COVID-19 pandemic period as 1 March to 31 December 2020. We compared observed IBD incidences during the pandemic to expected incidences, consistent with January 2014 to February 2020 trends. We conducted secondary analysis of a health care database to assess changes in testing by blood and cerebrospinal fluid (CSF) culture during the pandemic. RESULTS: Compared with expected incidences, the observed incidences of IBD due to S. pneumoniae, H. influenzae, GAS, and GBS were 58%, 60%, 28%, and 12% lower during the pandemic period of 2020, respectively. Declines from expected incidences corresponded closely with implementation of COVID-19-associated nonpharmaceutical interventions (NPIs). Significant declines were observed across all age and race groups, and surveillance sites for S. pneumoniae and H. influenzae. Blood and CSF culture testing rates during the pandemic were comparable to previous years. CONCLUSIONS: NPIs likely contributed to the decline in IBD incidence in the United States in 2020; observed declines were unlikely to be driven by reductions in testing.

BACKGROUND: Influenza virus and SARS-CoV-2 are significant causes of respiratory illness in children. METHODS: Influenza- and COVID-19-associated hospitalizations among children

Haemophilus influenzae (Hi) can cause meningitis and other serious invasive disease. Encapsulated Hi is classified into six serotypes (a-f) based on chemical composition of the polysaccharide capsule; unencapsulated strains are termed nontypeable Hi (NTHi). Hi serotype b (Hib) was the most common cause of bacterial meningitis in children in the pre-Hib vaccine era, and secondary transmission of Hi among children (e.g., to household contacts and in child care facilities) (1,2) led to the Advisory Committee on Immunization Practices (ACIP) recommendation for antibiotic chemoprophylaxis to prevent Hib disease in certain circumstances.* High Hib vaccination coverage since the 1990s has substantially reduced Hib disease, and other serotypes now account for most Hi-associated invasive disease in the United States (3). Nevertheless, CDC does not currently recommend chemoprophylaxis for contacts of persons with invasive disease caused by serotypes other than Hib and by NTHi (non-b Hi). Given this changing epidemiology, U.S. surveillance data were reviewed to investigate secondary cases of invasive disease caused by Hi. The estimated prevalence of secondary transmission was 0.32% among persons with encapsulated Hi disease (≤60 days of one another) and 0.12% among persons with NTHi disease (≤14 days of one another). Isolates from all Hi case pairs were genetically closely related, and all patients with potential secondary infection had underlying medical conditions. These results strongly suggest that secondary transmission of non-b Hi occurs. Expansion of Hi chemoprophylaxis recommendations might be warranted to control invasive Hi disease in certain populations in the United States, but further analysis is needed to evaluate the potential benefits against the risks, such as increased antibiotic use.

Immunocompromised persons are at increased risk for severe COVID-19-related outcomes, including intensive care unit (ICU) admission and death (1). Data on adults aged ≥18 years hospitalized with laboratory-confirmed COVID-19 from 10 U.S. states in the COVID-19-Associated Hospitalization Surveillance Network (COVID-NET) were analyzed to assess associations between immunocompromise and ICU admission and in-hospital death during March 1, 2020-February 28, 2022. Associations of COVID-19 vaccination status with ICU admission and in-hospital death were also examined during March 1, 2021-February 28, 2022. During March 1, 2020-February 28, 2022, among a sample of 22,345 adults hospitalized for COVID-19, 12.2% were immunocompromised. Among unvaccinated patients, those with immunocompromise had higher odds of ICU admission (adjusted odds ratio [aOR] = 1.26; 95% CI = 1.08-1.49) and in-hospital death (aOR = 1.34; 95% CI = 1.05-1.70) than did nonimmunocompromised patients. Among vaccinated patients,* those with immunocompromise had higher odds of ICU admission (aOR = 1.40; 95% CI = 1.01-1.92) and in-hospital death (aOR = 1.87; 95% CI = 1.28-2.75) than did nonimmunocompromised patients. During March 1, 2021-February 28, 2022, among nonimmunocompromised patients, patients who were vaccinated had lower odds of death (aOR = 0.58; 95% CI = 0.39-0.86) than did unvaccinated patients; among immunocompromised patients, odds of death between vaccinated and unvaccinated patients did not differ. Immunocompromised persons need additional protection from COVID-19 and using multiple known COVID-19 prevention strategies,† including nonpharmaceutical interventions, up-to-date vaccination of immunocompromised persons and their close contacts,§ early testing, and COVID-19 prophylactic (Evusheld) and early antiviral treatment,¶ can help prevent hospitalization and subsequent severe COVID-19 outcomes among immunocompromised persons.

During the ongoing mpox outbreak that began in 2022, severe oropharyngeal manifestations of mpox have been described (1-3). Co-infections have been diagnosed frequently in patients with mpox, notably sexually transmitted [...]

Clinical trials of COVID-19 vaccines currently authorized for emergency use in the United States (Pfizer-BioNTech, Moderna, and Janssen [Johnson & Johnson]) indicate that these vaccines have high efficacy against symptomatic disease, including moderate to severe illness (1-3). In addition to clinical trials, real-world assessments of COVID-19 vaccine effectiveness are critical in guiding vaccine policy and building vaccine confidence, particularly among populations at higher risk for more severe illness from COVID-19, including older adults. To determine the real-world effectiveness of the three currently authorized COVID-19 vaccines among persons aged ≥65 years during February 1-April 30, 2021, data on 7,280 patients from the COVID-19-Associated Hospitalization Surveillance Network (COVID-NET) were analyzed with vaccination coverage data from state immunization information systems (IISs) for the COVID-NET catchment area (approximately 4.8 million persons). Among adults aged 65-74 years, effectiveness of full vaccination in preventing COVID-19-associated hospitalization was 96% (95% confidence interval [CI] = 94%-98%) for Pfizer-BioNTech, 96% (95% CI = 95%-98%) for Moderna, and 84% (95% CI = 64%-93%) for Janssen vaccine products. Effectiveness of full vaccination in preventing COVID-19-associated hospitalization among adults aged ≥75 years was 91% (95% CI = 87%-94%) for Pfizer-BioNTech, 96% (95% CI = 93%-98%) for Moderna, and 85% (95% CI = 72%-92%) for Janssen vaccine products. COVID-19 vaccines currently authorized in the United States are highly effective in preventing COVID-19-associated hospitalizations in older adults. In light of real-world data demonstrating high effectiveness of COVID-19 vaccines among older adults, efforts to increase vaccination coverage in this age group are critical to reducing the risk for COVID-19-related hospitalization.

Among 513 adults aged 18-49 years without underlying medical conditions hospitalized with coronavirus disease 2019 (COVID-19) during March 2020-August 2020, 22% were admitted to an intensive care unit, 10% required mechanical ventilation, and 3 patients died (0.6%). These data demonstrate that healthy younger adults can develop severe COVID-19.

ObjectivesSome studies suggested more COVID-19-associated hospitalizations among racial and ethnic minorities. To inform public health practice, the COVID-19-associated Hospitalization Surveillance Network (COVID-NET) quantified associations between race/ethnicity, census tract socioeconomic indicators, and COVID-19-associated hospitalization rates.MethodsUsing data from COVID-NET population-based surveillance reported during March 1-April 30, 2020 along with socioeconomic and denominator data from the US Census Bureau, we calculated COVID-19-associated hospitalization rates by racial/ethnic and census tract-level socioeconomic strata.ResultsAmong 16,000 COVID-19-associated hospitalizations, 34.8% occurred among non-Hispanic White (White) persons, 36.3% among non-Hispanic Black (Black) persons, and 18.2% among Hispanic or Latino (Hispanic) persons. Age-adjusted COVID-19-associated hospitalization rate were 151.6 (95% Confidence Interval (CI): 147.1-156.1) in census tracts with >15.2%-83.2% of persons living below the federal poverty level (high-poverty census tracts) and 75.5 (95% CI: 72.9-78.1) in census tracts with 0%-4.9% of persons living below the federal poverty level (low-poverty census tracts). Among White, Black, and Hispanic persons living in high-poverty census tracts, age-adjusted hospitalization rates were 120.3 (95% CI: 112.3-128.2), 252.2 (95% CI: 241.4-263.0), and 341.1 (95% CI: 317.3-365.0), respectively, compared with 58.2 (95% CI: 55.4-61.1), 304.0 (95%: 282.4-325.6), and 540.3 (95% CI: 477.0-603.6), respectively, in low-poverty census tracts.ConclusionsOverall, COVID-19-associated hospitalization rates were highest in high-poverty census tracts, but rates among Black and Hispanic persons were high regardless of poverty level. Public health practitioners must ensure mitigation measures and vaccination campaigns address needs of racial/ethnic minority groups and people living in high-poverty census tracts.

Although COVID-19-associated hospitalizations and deaths have occurred more frequently in adults,† COVID-19 can also lead to severe outcomes in children and adolescents (1,2). Schools are opening for in-person learning, and many prekindergarten children are returning to early care and education programs during a time when the number of COVID-19 cases caused by the highly transmissible B.1.617.2 (Delta) variant of SARS-CoV-2, the virus that causes COVID-19, is increasing.§ Therefore, it is important to monitor indicators of severe COVID-19 among children and adolescents. This analysis uses Coronavirus Disease 2019-Associated Hospitalization Surveillance Network (COVID-NET)¶ data to describe COVID-19-associated hospitalizations among U.S. children and adolescents aged 0-17 years. During March 1, 2020-August 14, 2021, the cumulative incidence of COVID-19-associated hospitalizations was 49.7 per 100,000 children and adolescents. The weekly COVID-19-associated hospitalization rate per 100,000 children and adolescents during the week ending August 14, 2021 (1.4) was nearly five times the rate during the week ending June 26, 2021 (0.3); among children aged 0-4 years, the weekly hospitalization rate during the week ending August 14, 2021, was nearly 10 times that during the week ending June 26, 2021.** During June 20-July 31, 2021, the hospitalization rate among unvaccinated adolescents (aged 12-17 years) was 10.1 times higher than that among fully vaccinated adolescents. Among all hospitalized children and adolescents with COVID-19, the proportions with indicators of severe disease (such as intensive care unit [ICU] admission) after the Delta variant became predominant (June 20-July 31, 2021) were similar to those earlier in the pandemic (March 1, 2020-June 19, 2021). Implementation of preventive measures to reduce transmission and severe outcomes in children is critical, including vaccination of eligible persons, universal mask wearing in schools, recommended mask wearing by persons aged ≥2 years in other indoor public spaces and child care centers,†† and quarantining as recommended after exposure to persons with COVID-19.§§.

BACKGROUND: Respiratory syncytial virus (RSV) is a major cause of hospitalizations in young children. We estimated the burden of community-onset RSV-associated hospitalizations among US children aged

Most reported cases of coronavirus disease 2019 (COVID-19) in children aged

In the United States, [approximately equal to]37 million cases of coronavirus disease (COVID-19) and >620,000 deaths had been reported as of June 30, 2021 (1). Given the critical role of [...]

BackgroundFollowing Haemophilus influenzae serotype b (Hib) conjugate vaccine introduction in the 1980s, Hib disease in young children dramatically decreased, and epidemiology of invasive H. influenzae changed.MethodsActive surveillance for invasive H. influenzae disease was conducted through Active Bacterial Core surveillance sites. Incidence rates were directly standardized to the age and race distribution of the US population.ResultsDuring 2009-2015, the estimated mean annual incidence of invasive H. influenzae disease was 1.70 cases per 100000 population. Incidence was highest among adults aged ≥65 years (6.30) and children aged

BackgroundWe investigated the effect of influenza vaccination on disease severity in adults hospitalized with laboratory-confirmed influenza during 2013-14, a season in which vaccine viruses were antigenically similar to those circulating.MethodsWe analyzed data from the 2013-14 influenza season and used propensity score matching to account for the probability of vaccination within age strata (18-49, 50-64, and ≥65 years). Death, intensive care unit (ICU) admission, and hospital and ICU lengths of stay (LOS) were outcome measures for severity. Multivariable logistic regression and competing risk models were used to compare disease severity between vaccinated and unvaccinated patients, adjusting for timing of antiviral treatment and time from illness onset to hospitalization.ResultsInfluenza vaccination was associated with a reduction in the odds of in-hospital death among patients aged 18-49 years (adjusted odds ratios [aOR] = 0.21; 95% confidence interval [CI], 0.05 to 0.97), 50-64 years (aOR = 0.48; 95% CI, 0.24 to 0.97), and ≥65 years (aOR = 0.39; 95% CI, 0.17 to 0.66). Vaccination also reduced ICU admission among patients aged 18-49 years (aOR = 0.63; 95% CI, 0.42 to 0.93) and ≥65 years (aOR = 0.63; 95% CI, 0.48 to 0.81), and shortened ICU LOS among those 50-64 years (adjusted relative hazards [aRH] = 1.36; 95% CI, 1.06 to 1.74) and ≥65 years (aRH = 1.34; 95% CI, 1.06 to 1.73), and hospital LOS among 50-64 years (aRH = 1.13; 95% CI, 1.02 to 1.26) and ≥65 years (aRH = 1.24; 95% CI, 1.13 to 1.37).ConclusionsInfluenza vaccination during 2013-14 influenza season attenuated adverse outcome among adults that were hospitalized with laboratory-confirmed influenza.

In the United States, coronavirus disease (COVID-19) has disproportionately affected adults residing in long-term care facilities (LTCFs) (1-5). Outbreaks in LTCFs have caused high numbers of hospitalizations and deaths. Similar [...]

Meningococcal conjugate vaccines were licensed beginning in 2005 on the basis of serologic end points and recommended for use in adolescents. A single dose at age 11 to 12 years was expected to provide protection through late adolescence. We conducted a case-control evaluation of vaccine effectiveness (VE) and duration of protection of a meningococcal (groups A, C, W, and Y) polysaccharide diphtheria toxoid conjugate vaccine (MenACWY-D). Cases of culture- or polymerase chain reaction-confirmed serogroup A, C, W, and Y meningococcal disease among adolescents were identified through meningococcal disease surveillance sites in the United States from January 1, 2006, through August 31, 2013. Attempts were made to enroll 4 friend and school controls per case. VE was calculated using the generalized estimating equation, controlling for underlying medical conditions and smoking. Serogroup C accounted for 88 (49%), serogroup Y 80 (44%), and serogroup W 13 (7%) of enrolled cases. Thirty-six (20%) cases and 87 (44%) controls received MenACWY-D. The overall VE estimate 0 to 8 years postvaccination was 69% (51% to 80%); VE was 79% (49% to 91%) at

BackgroundAlthough human immunodeficiency virus (HIV) infection is an established risk factor for several bacterial infections, the association between HIV infection and meningococcal disease remains unclear.MethodsExpanded chart reviews were completed on persons with meningococcal disease and HIV infection reported from 2000 through 2008 from 9 US sites participating in an active population-based surveillance system for meningococcal disease. The incidence of meningococcal disease among patients meeting Centers for Disease Control and Prevention acquired immune deficiency syndrome (AIDS) surveillance criteria was estimated using data from the National HIV Surveillance System for the participating sites.ResultsThirty-three cases of meningococcal disease in individuals with HIV infection were reported from participating sites, representing 2.0% of all reported meningococcal disease cases. Most (75.8%) persons with HIV infection were adult males aged 25 to 64 years old. Among all meningococcal disease cases aged 25 to 64 years old, case fatality ratios were similar among HIV-infected and HIV-uninfected persons (13.3% vs 10.6%; P = .6). The cumulative, mean incidence of meningococcal disease among patients aged 25 to 64 years old with HIV infection ever classified as AIDS was 3.5 cases per 100000 person years (95% confidence interval [CI], 2.1-5.6), compared with 0.3 cases per 100000 person years (95% CI, 0.3-0.3) for persons of the same age group not reported to have AIDS (relative risk = 12.9; 95% CI, 7.9-20.9).ConclusionsIndividuals with HIV infection meeting the AIDS surveillance case definition have a higher incidence of meningococcal disease compared with the general adult population.

A healthcare provider unknowingly treated a patient with mpox and subsequently developed ocular mpox without rash. She breastfed during illness; her infant was not infected. This report addresses 3 challenges in mpox management and control: diagnosis in the absence of rash, exposures in healthcare settings, and management of lactating patients. [ABSTRACT FROM AUTHOR]

Objectives: Surveillance systems for unexplained deaths that might have an infectious etiology are rare. We examined the Minnesota Department of Health Unexplained Deaths and Critical Illnesses of Possible Infectious Etiology and Medical Examiner Infectious Deaths (UNEX/MED-X) surveillance system,—a system that expanded postmortem surveillance for infectious diseases during the COVID-19 pandemic by leveraging standard (medical examiner [ME]) and expanded (mortuary) surveillance to identify COVID-19–related deaths. Methods: MEs, coroners, or morticians collected postmortem swabs from decedents with an infectious prodrome or with SARS-CoV-2 exposure before death but with no known recent infectious disease testing. The Minnesota Department of Health Public Health Laboratory used nucleic acid amplification, viral culture, and standard algorithms to test specimens collected postmortem for SARS-CoV-2, influenza virus, and other infectious pathogens. We reviewed UNEX/MED-X data from March 2, 2020, through December 31, 2021, and characterized decedents by location of swab collection (ie, ME or mortuary). Results: From March 2, 2020, through December 31, 2021, the UNEX/MED-X surveillance system received samples from 182 decedents from mortuaries and 955 decedents from MEs. Mortuary decedents were older than ME decedents (median age, 78 vs 46 y). Seventy-three mortuary decedents (40.1%) and 197 ME decedents (20.6%) had SARS-CoV-2 detections. The UNEX/MED-X system identified 212 COVID-19–related deaths, representing 2.0% of total COVID-19–related deaths in Minnesota. Eighty-nine decedents (42.0%) were from racial and ethnic minority populations, representing 6.1% more COVID-19–related deaths among people from racial and ethnic minority populations than would have been detected without this surveillance system. Practice Implications: Expanded and standard UNEX/MED-X surveillance builds capacity and flexibility for responding to emerging public health threats. Similar programs should be considered elsewhere as resources allow. [ABSTRACT FROM AUTHOR]

In 2009, in the Active Bacterial Core surveillance sites, penicillin was not commonly used to treat meningococcal disease. This is likely because of inconsistent availability of antimicrobial susceptibility testing and ease of use of third-generation cephalosporins. Consideration of current practices may inform future meningococcal disease management guidelines.

ObjectiveTranscripts from admission chest radiographs could aid in identification of pneumonia cases for public health surveillance. We assessed the reliability of radiographic data abstraction and performance of radiographic key terms to identify pneumonia in patients hospitalized with laboratory-confirmed influenza virus infection.MethodsWe used data on patients hospitalized with laboratory-confirmed influenza virus infection from October 2008 through December 2009 from 10 geographically diverse U.S. study sites participating in the Influenza Hospitalization Surveillance Network (FluSurv-NET). Radiographic key terms (i.e., bronchopneumonia, consolidation, infiltrate, airspace density, and pleural effusion) were abstracted from final impressions of chest radiograph reports. We assessed the reliability of radiographic data abstraction by examining the percent agreement and Cohen's k statistic between clinicians and surveillance staff members. Using a composite reference standard for presence or absence of pneumonia based on International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes and discharge summary data, we calculated sensitivity, specificity, positive predictive value (PPV), and percent agreement for individual and combined radiographic key terms.ResultsFor each radiographic key term, the percent agreement between clinicians and surveillance staff members ranged from 89.4% to 98.6% and Cohen's k ranged from 0.46 (moderate) to 0.84 (almost perfect). The combination of bronchopneumonia or consolidation or infiltrate or airspace density terms had sensitivity of 66.5%, specificity of 89.2%, PPV of 80.4%, and percent agreement of 80.1%. Adding pleural effusion did not result in significant changes in sensitivity, specificity, PPV, or percent agreement.ConclusionRadiographic key terms abstracted by surveillance staff members from final impressions of chest radiograph reports had moderate to almost perfect reliability and could be used to identify pneumonia among patients hospitalized with laboratory-confirmed influenza virus infection. This method can inform pneumonia surveillance and aid in public health response.