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Effectiveness of seasonal influenza vaccinations against laboratory-confirmed influenza-associated infections among Singapore military personnel in 2010-2013.

ABSTRACT: BACKGROUND: Limited information is available about seasonal influenza vaccine effectiveness (VE) in tropical communities. OBJECTIVES: Virus subtype-specific VE was determined for all military service personnel in the recruit camp and three other non-recruit camp in Singapore's Armed Forces from 1 June 2009 to 30 June 2012. METHODS: Consenting servicemen underwent nasal washes, which were tested with RT-PCR and subtyped. The test positive case and test negative control design was used to estimate the VE. To estimate the overall effect of the programme on new recruits, we used an ecological time series approach. RESULTS: A total of 7016 consultations were collected. The crude estimates for the VE of the triavalent vaccine against both influenza A(H1N1)pdm09 and influenza B were 84% (95% CI 78-88%, 79-86%, respectively). Vaccine efficacy against influenza A(H3N2) was markedly lower (VE 33%, 95% CI -4% to 57%). An estimated 70% (RR = 0.30; 95% CI 0.11-0.84), 39% (RR = 0.61;0.25-1.43) and 75% (RR = 0.25; 95% CI 0.11-0.50) reduction in the risk of influenza A(H1N1)pdm09, influenza A(H3N2) and influenza B infections, respectively, in the recruit camp during the post-vaccination period compared with during the pre-vaccination period was observed. CONCLUSIONS: Overall, the blanket influenza vaccine programme in Singapore's Armed Forces has had a moderate to high degree of protection against influenza A(H1N1)pdm09 and influenza B, but not against influenza A(H3N2). Blanket influenza vaccination is recommended for all military personnel.

SUBMITTER: Ho HP

PROVIDER: S-EPMC4181820 | biostudies-other | 2014 Sep

REPOSITORIES: biostudies-other

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Effectiveness of seasonal influenza vaccinations against laboratory-confirmed influenza-associated infections among Singapore military personnel in 2010-2013.

Ho Hin Peow HP Zhao Xiahong X Pang Junxiong J Chen Mark I-C MI Lee Vernon J M VJ Ang Li Wei LW Lin Raymond V Tzer Pin RV Gao Christine Q CQ Hsu Li Yang LY Cook Alex R AR

Influenza and other respiratory viruses 20140514 5

<h4>Background</h4>Limited information is available about seasonal influenza vaccine effectiveness (VE) in tropical communities.<h4>Objectives</h4>Virus subtype-specific VE was determined for all military service personnel in the recruit camp and three other non-recruit camp in Singapore's Armed Forces from 1 June 2009 to 30 June 2012.<h4>Methods</h4>Consenting servicemen underwent nasal washes, which were tested with RT-PCR and subtyped. The test positive case and test negative control design w ...[more]

PMID: 24828687

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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.

Project description:BackgroundOne dose of pandemic influenza vaccine Pandemrix (GlaxoSmithKline) was offered to the entire population of Finland in 2009-10. We conducted a prospective clinical cohort study to determine the vaccine effectiveness in preventing febrile laboratory-confirmed influenza infection during the influenza season 2009-10 and continued the study in 2010-11.MethodsIn total, 3,518 community dwelling adults aged 18-75 years living in Tampere city were enrolled. The participants were not assigned to any vaccination regimen, but they could participate in the study regardless of their vaccination status or intention to be vaccinated with the pandemic or seasonal influenza vaccine. They were asked to report if they received Pandemrix in 2009-10 and/or trivalent influenza vaccine in 2010-11. Vaccinations were verified from medical records. The participants were instructed to report all acute symptoms of respiratory tract infection with fever (at least 38°C) and pneumonias to the study staff. Nasal and oral swabs were obtained within 5-7 days after symptom onset and influenza-specific RNA was identified by reverse transcription polymerase chain reaction.ResultsIn 2009-10, the estimated vaccine effectiveness was 81% (95%CI 30-97). However, the vaccine effectiveness could not be estimated reliably, because only persons in prioritized groups were vaccinated before/during the first pandemic wave and many participants were enrolled when they already had the symptoms of A(H1N1)pdm09 influenza infection. In 2010-11, 2,276 participants continued the follow-up. The vaccine effectiveness, adjusted for potential confounding factors was 81% (95%CI 41-96) for Pandemrix only and 88% (95%CI 63-97) for either Pandemrix or trivalent influenza vaccine 2010-11 or both, respectively.ConclusionVaccination with an AS03-adjuvanted pandemic vaccine in 2009-10 was still effective in preventing A(H1N1)pdm09 influenza during the following epidemic season in 2010-11.Trial registrationClinicalTrials.gov NCT01024725. NCT01206114.

Project description:During the 2009 influenza pandemic both seasonal and 2009 pandemic vaccines were recommended. We conducted a randomized trial of monovalent 2009-H1N1 vaccine and seasonal trivalent inactivated influenza vaccine (IIV3) given sequentially or concurrently to adults.Adults randomized to 4 study groups and stratified by age (18-64 and ?65 years) received 1 dose of seasonal IIV3 or placebo and 2 doses of 2009-H1N1 vaccine or placebo in one of 4 combinations, i.e., H1N1+Placebo/H1N1+Placebo/IIV3 (HP/HP/V3), H1N1+IIV3/H1N1+Placebo/Placebo (HV3/HP/P), H1N1+Placebo/H1N1+IIV3/Placebo (HP/HV3/P), and IIV3+Placebo/H1N1+Placebo/H1N1 (V3P/HP/H). Intramuscular injections were given three times at 21 day intervals. Sera for antibody assays were obtained prior to and 21 days after each vaccination. Reactogenicity and adverse events were monitored.Eight hundred-five (805) adults were enrolled. All combinations of vaccines were safe and well tolerated. In general, one dose of 2009-H1N1 and one dose of IIV3, regardless of sequence or concurrency of administration, were immunogenic in adults. There were no significant differences in geometric mean titers (GMT) or the proportions of subjects with ?4-fold rise in antibody responses and titers ?40 for any vaccine group or between age strata for 2009-H1N1 after the first or second dose, although the vaccine sequence affected the titers to the IIV3 antigens. Hemagglutination inhibition antibody (HAI) GMTs against 2009-H1N1 for the combined age strata 21 days after the first 2009-H1N1 dose were 190.4, 182.1, 232.9 and 157.5 for HP/HP/V3, HV3/HP/P, HP/HV3/P and V3P/HP/H, respectively. While IIV3 GMTs were adequate they were generally lower than the 2009-H1N1 GMTs. In a subset of subjects, there was good correlation between HAI and microneutralization (MN) titers (Spearman's correlation coefficient 0.92).All vaccine combinations were generally well tolerated. Immune responses to one dose of 2009-H1N1 were adequate regardless of the sequence of vaccination in all age groups, but the sequence affected titers to IIV3 antigens.

Dataset Information

Effectiveness of seasonal influenza vaccinations against laboratory-confirmed influenza-associated infections among Singapore military personnel in 2010-2013.

Publications

Effectiveness of seasonal influenza vaccinations against laboratory-confirmed influenza-associated infections among Singapore military personnel in 2010-2013.

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