Burden of influenza-associated respiratory hospitalizations in the Americas, 2010-2015.

BACKGROUND: Despite having influenza vaccination policies and programs, countries in the Americas underutilize seasonal influenza vaccine, in part because of insufficient evidence about severe influenza burden. We aimed to estimate the annual burden of influenza-associated respiratory hospitalizations in the Americas. METHODS: Thirty-five countries in the Americas with national influenza surveillance were invited to provide monthly laboratory data and hospital discharges for respiratory illness (International Classification of Diseases 10th edition J codes 0-99) during 2010-2015. In three age-strata (<5, 5-64, and ≥65 years), we estimated the influenza-associated hospitalizations rate by multiplying the monthly number of respiratory hospitalizations by the monthly proportion of influenza-positive samples and dividing by the census population. We used random effects meta-analyses to pool age-group specific rates and extrapolated to countries that did not contribute data, using pooled rates stratified by age group and country characteristics found to be associated with rates. RESULTS: Sixteen of 35 countries (46%) contributed primary data to the analyses, representing 79% of the America's population. The average pooled rate of influenza-associated respiratory hospitalization was 90/100,000 population (95% confidence interval 61-132) among children aged <5 years, 21/100,000 population (13-32) among persons aged 5-64 years, and 141/100,000 population (95-211) among persons aged ≥65 years. We estimated the average annual number of influenza-associated respiratory hospitalizations in the Americas to be 772,000 (95% credible interval 716,000-829,000). CONCLUSIONS: Influenza-associated respiratory hospitalizations impose a heavy burden on health systems in the Americas. Countries in the Americas should use this information to justify investments in seasonal influenza vaccination-especially among young children and the elderly.

Hospitalization costs due to severe acute respiratory infection (SARI) in three Central American countries / Costos de hospitalización de infección respiratoria aguda grave (IRAG) en tres países de América Central

Objective: To estimate the direct medical costs of severe acute respiratory infection (SARI) in children and adults from three Central American countries with a bottom-up costing approach. Methods: The costs of inpatients treatment were estimated through the retrospective bottom-up costing in a randomized sample of clinical records from SARI patients treated in teaching tertiary hospitals during 2009 - 2011 period. Activities incurred per patient were registered and a setting-specific cost per activity was acquired. Average cost per patient in the group of children and elderly adults was estimated for each country. In Nicaragua, only the pediatric population was included. Costs were expressed in local currency (2011), American dollars, and international dollars (2005) for country comparison. Results: The care cost per case in children in Guatemala was the cheaper (I$971.95) compared to Nicaragua (I$1,431.96) and Honduras (I$1,761.29). In adults, the treatment cost for Guatemala was the more expensive: I$4,065.00 vs. I$2,707.91 in Honduras. Conclusion: Bottom-up costing of SARI cases allowed the mean estimates per treated case that could have external validity for the target population diagnosed in hospitals with similar epidemiological profiles and level of complexity for the study countries. This information is very relevant for the decision-making.

Objetivo: Estimar los costos directos de la atención de infección respiratoria aguda (IRAG) en niños y adultos en tres países de América Central. Métodos: Los costos de pacientes hospitalizados fueron estimados a través de análisis retrospectivo en una muestra aleatoria de registros de historias clínicas de casos de IRAG tratado en hospitales universitarios durante el periodo 2009-2011. Las actividades incurridas por paciente fueron registradas y un costo especifico para cada sitio fue estimado. El costo por cada niño y adulto mayor fue estimado para cada país. En Nicaragua sólo se incluyó población pediátrica. Los costos fueron expresados en moneda local (2011), dolar americano y dolar internacional (2005). Resultados: El costo por caso en niños en Guatemala fue el más barato (I$971.95) comparado al de Nicaragua (I$1,431.96) y Honduras (I$1,761.29). En adultos, el costo de tratamiento para Guatemala fue el más costoso: I$4,065.00 vs. I$2,707.91 en Honduras. Conclusión: Los costos de tratar casos IRAG estimados a partir de costos promedios pro caso pueden tener validez externa para hospitales con perfiles epidemiologicos similares y nivel de complejidad de atención para los países del estudio. Esta información es muy relevante para la toma de decisiones.

Pilot to evaluate the feasibility of measuring seasonal influenza vaccine effectiveness using surveillance platforms in Central-America, 2012.

BACKGROUND: Since 2004, the uptake of seasonal influenza vaccines in Latin America and the Caribbean has markedly increased. However, vaccine effectiveness (VE) is not routinely measured in the region. We assessed the feasibility of using routine surveillance data collected by sentinel hospitals to estimate influenza VE during 2012 against laboratory-confirmed influenza hospitalizations in Costa-Rica, El Salvador, Honduras and Panama. We explored the completeness of variables needed for VE estimation. METHODS: We conducted the pilot case-control study at 23 severe acute respiratory infections (SARI) surveillance hospitals. Participant inclusion criteria included children 6 months-11 years and adults ≥60 years targeted for vaccination and hospitalized for SARI during January-December 2012. We abstracted information needed to estimate target group specific VE (i.e., date of illness onset and specimen collection, preexisting medical conditions, 2012 and 2011 vaccination status and date, and pneumococcal vaccination status for children and adults) from SARI case-reports and for children ≤9 years, inquired about the number of annual vaccine doses given. A case was defined as an influenza virus positive by RT-PCR in a person with SARI, while controls were RT-PCR negative. We recruited 3 controls per case from the same age group and month of onset of symptoms. RESULTS: We identified 1,186 SARI case-patients (342 influenza cases; 849 influenza-negative controls), of which 994 (84 %) had all the information on key variables sought. In 893 (75 %) SARI case-patients, the vaccination status field was missing in the SARI case-report forms and had to be completed using national vaccination registers (36 %), vaccination cards (30 %), or other sources (34 %). After applying exclusion criteria for VE analyses, 541 (46 %) SARI case-patients with variables necessary for the group-specific VE analyses were selected (87 cases, 236 controls among children; 64 cases, 154 controls among older adults) and were insufficient to provide precise regional estimates (39 % for children and 25 % for adults of minimum sample size needed). CONCLUSIONS: Sentinel surveillance networks in middle income countries, such as some Latin American and Caribbean countries, could provide a simple and timely platform to estimate regional influenza VE annually provided SARI forms collect all necessary information.