Dataset Information

Effectiveness of Seasonal Influenza Vaccination in Children in Senegal During a Year of Vaccine Mismatch: A Cluster-randomized Trial.

ABSTRACT: BACKGROUND:The population effects of influenza vaccination in children have not been extensively studied, especially in tropical, developing countries. In rural Senegal, we assessed the total (primary objective) and indirect effectiveness of a trivalent inactivated influenza vaccine (IIV3). METHODS:In this double-blind, cluster-randomized trial, villages were randomly allocated (1:1) for the high-coverage vaccination of children aged 6 months through 10 years with either the 2008-09 northern hemisphere IIV3 or an inactivated polio vaccine (IPV). Vaccinees were monitored for serious adverse events. All village residents, vaccinated and unvaccinated, were monitored for signs and symptoms of influenza illness using weekly home visits and surveillance in designated clinics. The primary outcome was all laboratory-confirmed symptomatic influenza. RESULTS:Between 23 May and 11 July 2009, 20 villages were randomized, and 66.5% of age-eligible children were enrolled (3918 in IIV3 villages and 3848 in IPV villages). Follow-up continued until 28 May 2010. There were 4 unrelated serious adverse events identified. Among vaccinees, the total effectiveness against illness caused by the seasonal influenza virus (presumed to all be drifted A/H3N2, based on antigenic characterization data) circulating at high rates among children was 43.6% (95% confidence interval [CI] 18.6-60.9%). The indirect effectiveness against seasonal A/H3N2 was 15.4% (95% CI -22.0 to 41.3%). The total effectiveness against illness caused by the pandemic influenza virus (A/H1N1pdm09) was -52.1% (95% CI -177.2 to 16.6%). CONCLUSIONS:IIV3 provided statistically significant, moderate protection to children in Senegal against circulating, pre-2010 seasonal influenza strains, but not against A/H1N1pdm09, which was not included in the vaccine. No indirect effects were measured. Further study in low-resource populations is warranted. CLINICAL TRIALS REGISTRATION:NCT00893906.

SUBMITTER: Diallo A

PROVIDER: S-EPMC6821165 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Effectiveness of Seasonal Influenza Vaccination in Children in Senegal During a Year of Vaccine Mismatch: A Cluster-randomized Trial.

Diallo Aldiouma A Diop Ousmane M OM Diop Doudou D Niang Mbayame Nd MN Sugimoto Jonathan D JD Ortiz Justin R JR Faye El Hadji Abdourahmane EHA Diarra Bou B Goudiaby Deborah D Lewis Kristen D C KDC Emery Shannon L SL Zangeneh Sahar Z SZ Lafond Kathryn E KE Sokhna Cheikh C Halloran M Elizabeth ME Widdowson Marc-Alain MA Neuzil Kathleen M KM Victor John C JC

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 20191001 10

<h4>Background</h4>The population effects of influenza vaccination in children have not been extensively studied, especially in tropical, developing countries. In rural Senegal, we assessed the total (primary objective) and indirect effectiveness of a trivalent inactivated influenza vaccine (IIV3).<h4>Methods</h4>In this double-blind, cluster-randomized trial, villages were randomly allocated (1:1) for the high-coverage vaccination of children aged 6 months through 10 years with either the 2008- ...[more]

PMID: 30689757

Similar Datasets

Project description:BackgroundSeasonal influenza is a major cause of mortality worldwide. Routine immunization of children has the potential to reduce this mortality through both direct and indirect protection, but has not been adopted by any low- or middle-income countries. We developed a framework to evaluate the cost-effectiveness of influenza vaccination policies in developing countries and used it to consider annual vaccination of school- and preschool-aged children with either trivalent inactivated influenza vaccine (TIV) or trivalent live-attenuated influenza vaccine (LAIV) in Thailand. We also compared these approaches with a policy of expanding TIV coverage in the elderly.Methods and findingsWe developed an age-structured model to evaluate the cost-effectiveness of eight vaccination policies parameterized using country-level data from Thailand. For policies using LAIV, we considered five different age groups of children to vaccinate. We adopted a Bayesian evidence-synthesis framework, expressing uncertainty in parameters through probability distributions derived by fitting the model to prospectively collected laboratory-confirmed influenza data from 2005-2009, by meta-analysis of clinical trial data, and by using prior probability distributions derived from literature review and elicitation of expert opinion. We performed sensitivity analyses using alternative assumptions about prior immunity, contact patterns between age groups, the proportion of infections that are symptomatic, cost per unit vaccine, and vaccine effectiveness. Vaccination of children with LAIV was found to be highly cost-effective, with incremental cost-effectiveness ratios between about 2,000 and 5,000 international dollars per disability-adjusted life year averted, and was consistently preferred to TIV-based policies. These findings were robust to extensive sensitivity analyses. The optimal age group to vaccinate with LAIV, however, was sensitive both to the willingness to pay for health benefits and to assumptions about contact patterns between age groups.ConclusionsVaccinating school-aged children with LAIV is likely to be cost-effective in Thailand in the short term, though the long-term consequences of such a policy cannot be reliably predicted given current knowledge of influenza epidemiology and immunology. Our work provides a coherent framework that can be used for similar analyses in other low- and middle-income countries.

Project description:BackgroundChina has a high burden of influenza-associated illness among children. We aimed to evaluate the cost-effectiveness of introducing government-funded influenza vaccination to children in China (fully-funded policy) compared with the status quo (self-paid policy).MethodsA decision tree model was developed to calculate the economic and health outcomes, from a societal perspective, using national- and provincial-level data. The incremental cost-effectiveness ratio (ICER) [incremental costs per quality-adjusted life year (QALY) gained] was used to compare the fully-funded policy with the self-paid policy under the willingness-to-pay threshold equivalent to national and provincial GDP per capita. Sensitivity analyses were performed and various scenarios were explored based on real-world conditions, including incorporating indirect effect into the analysis.ResultsCompared to the self-paid policy, implementation of a fully-funded policy could prevent 1,444,768 [95% uncertainty range (UR): 1,203,446-1,719,761] symptomatic cases, 92,110 (95% UR: 66,953-122,226) influenza-related hospitalizations, and 6494 (95% UR: 4590-8962) influenza-related death per season. The fully-funded policy was cost-effective nationally (7964 USD per QALY gained) and provincially for 13 of 31 provincial-level administrative divisions (PLADs). The probability of a funded vaccination policy being cost-effective was 56.5% nationally, and the probability in 9 of 31 PLADs was above 75%. The result was most sensitive to the symptomatic influenza rate among children under 5 years [ICER ranging from - 25,612 (cost-saving) to 14,532 USD per QALY gained]. The ICER of the fully-funded policy was substantially lower (becoming cost-saving) if the indirect effects of vaccination were considered.ConclusionsIntroducing a government-funded influenza policy for children is cost-effective in China nationally and in many PLADs. PLADs with high symptomatic influenza rate and influenza-associated mortality would benefit the most from a government-funded influenza vaccination program.

Project description:ImportanceSome studies have reported negative effects of prior-season influenza vaccination. Prior-season influenza vaccination effects on vaccine effectiveness (VE) in children are not well understood.ObjectiveTo assess the association of prior-season influenza vaccination with subsequent VE in children aged 2 to 17 years.Design, setting, and participantsThis multiseason, test-negative case-control study was conducted in outpatient clinics at 4 US sites among children aged 2 to 17 years with a medically attended febrile acute respiratory illness. Participants were recruited during the 2013-2014, 2014-2015, and 2015-2016 seasons when influenza circulated locally. Cases were children with influenza confirmed by reverse-transcription polymerase chain reaction. Test-negative control individuals were children with negative test results for influenza.ExposuresVaccination history, including influenza vaccine type received in the enrollment season (live attenuated influenza vaccine [LAIV], inactivated influenza vaccine [IIV], or no vaccine) and season before enrollment (LAIV, IIV, or no vaccine), determined from medical records and immunization registries.Main outcomes and measuresLAIV and IIV effectiveness by influenza type and subtype (influenza A[H1N1]pdm09, influenza A[H3N2], or influenza B), estimated as 100 × (1 - odds ratio) in a logistic regression model with adjustment for potential confounders. Prior season vaccination associations were assessed with an interaction term.ResultsOf 3369 children (1749 [52%] male; median age, 6.6 years [range, 2-17 years]) included in the analysis, 772 (23%) had a positive test result for influenza and 1674 (50%) were vaccinated in the enrollment season. Among LAIV recipients, VE against influenza A(H3N2) was higher among children vaccinated in both the enrollment and 1 prior season (50.3% [95% CI, 17.0% to 70.2%]) than among those without 1 prior season vaccination (-82.4% [95% CI, -267.5% to 9.5%], interaction P < .001). The effectiveness of LAIV against influenza A(H1N1)pdm09 was not associated with prior season vaccination among those with prior season vaccination (47.5% [95% CI, 11.4% to 68.9%]) and among those without prior season vaccination (7.8% [95% CI, -101.9% to 57.9%]) (interaction P = .37). Prior season vaccination was not associated with effectiveness of IIV against influenza A(H3N2) (38.7% [95% CI, 6.8% to 59.6%] among those with prior-season vaccination and 23.2% [95% CI, -38.3% to 57.4%] among those without prior-season vaccination, interaction P = .16) or with effectiveness of IIV against influenza A[H1N1]pdm09 (72.4% [95% CI, 56.0% to 82.7%] among those with prior season vaccination and 67.5% [95% CI, 32.1% to 84.4%] among those without prior season vaccination, interaction P = .93). Residual protection from prior season vaccination only (no vaccination in the enrollment season) was observed for influenza B (LAIV: 60.0% [95% CI, 36.8% to 74.7%]; IIV: 60.0% [36.9% to 74.6%]). Similar results were observed in analyses that included repeated vaccination in 2 and 3 prior seasons.Conclusions and relevanceInfluenza VE varied by influenza type and subtype and vaccine type, but prior-season vaccination was not associated with reduced VE. These findings support current recommendations for annual influenza vaccination of children.

Project description:BackgroundDespite widespread utilization of influenza vaccines, effectiveness (VE) has not been routinely measured in Latin America.MethodsWe used a case test-negative control design to estimate trivalent inactivated influenza VE against laboratory-confirmed influenza among hospitalized children aged 6months-5years and adults aged ≥60years which are age-groups targeted for vaccination. We sought persons with severe acute respiratory infections (SARI), hospitalized at 71 sentinel hospitals in Argentina, Brazil, Chile, Colombia, Costa Rica, El Salvador, Honduras, Panama, and Paraguay during January-December 2013. Cases had an influenza virus infection confirmed by real-time reverse transcription PCR (rRT-PCR); controls had a negative rRT-PCR result for influenza viruses. We used a two-stage random effects model to estimate pooled VE per target age-group, adjusting for the month of illness onset, age and preexisting medical conditions.ResultsWe identified 2620 SARI patients across sites: 246 influenza cases and 720 influenza-negative controls aged ≤5years and 448 cases and 1206 controls aged ≥60years. The most commonly identified subtype among participants (48%) was the influenza A(H1N1)pdm09 virus followed by influenza A(H3N2) (34%) and influenza B (18%) viruses. Among children, the adjusted VE of full vaccination (one dose for previously vaccinated or two if vaccine naïve) against any influenza virus SARI was 47% (95% confidence interval [CI]: 14-71%); VE was 58% (95% CI: 16-79%) against influenza A(H1N1)pdm09, and 65% (95% CI: -9; 89%) against influenza A(H3N2) viruses associated SARI. Crude VE of full vaccination against influenza B viruses associated SARI among children was 3% (95% CI: -150; 63). Among adults aged ≥60years, adjusted VE against any influenza SARI was 48% (95% CI: 34-60%); VE was 54% (95% CI: 37-69%) against influenza A(H1N1)pdm09, 43% (95% CI: 18-61%) against influenza A(H3N2) and 34% (95% CI: -4; 58%) against B viruses associated SARI.ConclusionInfluenza vaccine provided moderate protection against severe influenza illness among fully vaccinated young children and older adults, supporting current vaccination strategies.

Dataset Information

Effectiveness of Seasonal Influenza Vaccination in Children in Senegal During a Year of Vaccine Mismatch: A Cluster-randomized Trial.

Publications

Effectiveness of Seasonal Influenza Vaccination in Children in Senegal During a Year of Vaccine Mismatch: A Cluster-randomized Trial.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets