Ruth Emerson

Annual estimates of the influenza disease burden provide information to evaluate programs and allocate resources. We used a multiplier method with routine population-based surveillance data on influenza hospitalization in the United States to correct for under-reporting and estimate the burden of influenza for seasons after the 2009 pandemic. Five sites of the Influenza Hospitalization Surveillance Network (FluSurv-NET) collected data on the frequency and sensitivity of influenza testing during two seasons to estimate under-detection. Population-based rates of influenza-associated hospitalization and Intensive Care Unit admission from 2010-2013 were extrapolated to the U.S. population from FluSurv-NET and corrected for under-detection. Influenza deaths were calculated using a ratio of deaths to hospitalizations. We estimated that influenza-related hospitalizations were under-detected during 2010-11 by a factor of 2.1 (95%CI 1.7-2.9) for age < 18 years, 3.1 (2.4-4.5) for ages 18-64 years, and 5.2 (95%CI 3.8-8.3) for age 65+. Results were similar in 2011-12. Extrapolated estimates for 3 seasons from 2010-2013 included: 114,192-624,435 hospitalizations, 18,491-95,390 ICU admissions, and 4,915-27,174 deaths per year; 54-70% of hospitalizations and 71-85% of deaths occurred among adults aged 65+. Influenza causes a substantial disease burden in the U.S. that varies by age and season. Periodic estimation of multipliers across multiple sites and age groups improves our understanding of influenza detection in sentinel surveillance systems. Adjusting surveillance data using a multiplier method is a relatively simple means to estimate the impact of influenza and the subsequent value of interventions to prevent influenza.

OBJECTIVE: Early initiation of antiretroviral treatment (ART) at CD4 cell count ≥ 500 cells per microliter reduces morbidity and mortality in HIV-infected adults. We determined the proportion of HIV-infected people with high viral load (VL) for whom transmission prevention would be an additional benefit of early treatment. DESIGN: A randomly selected subset of a nationally representative sample of HIV-infected adults in Swaziland in 2012. METHODS: Eight to 12 months after a national survey to determine adult HIV prevalence, 1067 of 5802 individuals identified as HIV-infected were asked to participate in a follow-up cross-sectional assessment. CD4 cell enumeration, VL measurements, and ART status were obtained to estimate the proportion of currently untreated adults and of the entire HIV-infected population with high VL (≥ 1000 copies/mL) whose treatment under a test-and-treat or VL threshold eligibility strategy would reduce HIV transmission. RESULTS: Of the 927 (87% of 1067) participants enrolled, 466 (50%) reported no ART use. Among them, 424 (91%) had VL ≥ 1000 copies per milliliter; of these, 148 (35%) were eligible for ART at the then existing CD4 count threshold of <350 cells per microliter; an additional 107 (25%) were eligible with expanded CD4 criterion of <500 cells per microliter; and 169 (40%) remained ART ineligible. Thus, 36% of the 466 currently untreated and 18% of the total 927 had high VL yet remained ART ineligible under a CD4 criterion of <500 cells per microliter. CONCLUSIONS: A test-and-treat or VL threshold for treatment eligibility is necessary to maximize the HIV transmission prevention benefits of ART.