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Concept: Influenza vaccines

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Live attenuated influenza vaccine (LAIV) is safe in healthy children ⩾2years. The original clinical trials excluded individuals with underlying conditions; however, post-marketing data suggest LAIV may be safe for these populations.

Concepts: Medicine, Public health, Vaccine, Vaccination, Influenza, Influenza vaccine, Live attenuated influenza vaccine, Influenza vaccines

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This analysis examined potential causes of the lack of vaccine effectiveness (VE) of live attenuated influenza vaccine (LAIV) against A/H1N1pdm09 viruses in the United States (US) during the 2013-2014 season. Laboratory studies have demonstrated reduced thermal stability of A/California/07/2009, the A/H1N1pdm09 strain utilized in LAIV from 2009 through 2013-2014.

Concepts: Virus, Vaccine, Vaccination, United States, Influenza, Influenza vaccine, Live attenuated influenza vaccine, Influenza vaccines

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Prior studies showed that live attenuated influenza vaccine (LAIV) is more effective than inactivated influenza vaccine (IIV) in children aged 2-8 years, supporting the Centers for Disease Control and Prevention (CDC) recommendations in 2014 for preferential LAIV use in this age group. However, 2014-2015 U.S. effectiveness data indicated relatively poor effectiveness of both vaccines, leading CDC in 2015 to no longer prefer LAIV.

Concepts: Pneumonia, Vaccine, Vaccination, Influenza, Influenza vaccine, Live attenuated influenza vaccine, Vaccines, Influenza vaccines

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The goal of this research is to develop stable formulations for live attenuated influenza vaccines (LAIV) by employing the drying methods freeze drying, spray drying, and foam drying.

Concepts: Vaccine, Influenza, Influenza vaccine, Food preservation, Live attenuated influenza vaccine, Vaccines, Influenza vaccines, Unit operations

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A live attenuated influenza vaccine (LAIV) was offered during the 2012-13 influenza season in Quebec, Canada, to children aged between 2 and 17 years with chronic medical conditions. Despite the offer, uptake of the vaccine was low. We assessed the perceptions and opinions about seasonal influenza vaccination and LAIV use among vaccine providers who participated in the 2012-13 campaign. More than 70% of them thought that LAIV was safe and effective and more than 90% considered that the vaccine was well-received by parents and healthcare professionals. According to respondents, the most frequent concerns of parents about LAIV were linked to vaccine efficacy. LAIV is well-accepted by vaccine providers involved in influenza vaccination clinics, but more information about the vaccine and the recommendations for its use are needed to increase vaccine uptake.

Concepts: Medicine, Vaccine, Vaccination, Influenza, Influenza vaccine, Live attenuated influenza vaccine, Vaccines, Influenza vaccines

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Four randomized, double-blind, placebo-controlled studies in 6090 children that investigated the efficacy of live attenuated influenza vaccine (LAIV) upon revaccination of children against laboratory-confirmed cases of influenza in consecutive seasons were reviewed. The efficacy in season 2 of LAIV administered over 2 consecutive seasons was 86.7% (95 % CI: 76.8%, 92.4%) against strains antigenically similar to those contained in the vaccine. The additional efficacy of LAIV administered in season 2 compared to LAIV recipients in season 1 only was 58.4% (28.3%, 75.9%). LAIV administered over 2 consecutive seasons also was more efficacious than was LAIV administered in season 2 only (relative efficacy: 53.9% [17.4%, 74.3%]). Residual efficacy of LAIV administered in season 1 only compared to placebo administered in two consecutive seasons was 56.4% (37.0%, 69.8%). This review did not find any evidence of decreasing efficacy of LAIV when administered during 2 consecutive seasons.

Concepts: Vaccine, Randomized controlled trial, Influenza, Placebo, Influenza vaccine, Live attenuated influenza vaccine, Vaccines, Influenza vaccines

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Since 2012, there are not only trivalent inactivated influenza vaccines (TIV) but also live attenuated influenza vaccines (LAIV) available for children aged 2-17 years in Germany. The Saxony-Anhalt State Office for Consumer Protection conducted a test-negative case-control-study. The aim of the study was to identify the effectiveness of LAIV and TIV against a confirmed influenza diagnosis in children and adolescents in Saxony-Anhalt in the season 2012/13. The children had nasal swabs taken, which were further diagnosed in a laboratory using the PCR method. 834 patients of 15 voluntarily participating paediatric surgeries in Saxony-Anhalt were analysed by multivariate logistic regression with STATA 12. Controlling for age group, gender and month of the disease’s onset showed an effectiveness of all vaccines amongst the 2-17 years old (38% with 95% CI: 0.8-61%; p=0.046). A differentiation according to LAIV and TIV demonstrated a significant effectiveness for LAIV (84%) in children of all ages (95% CI: 45-95%, p=0.004). After stratification for age groups LAIV was proven efficient in children aged 2-6 years (90% with 95% CI: 20-99%, p=0.03), whilst it led to a non-significant result in children aged 7-17 years (74% with 95% CI: -32-95%, p=0.106). There was no significant effectiveness of TIV seen in any age group.The Saxony-Anhalt State Office for Consumer Protection endorses the use of LAIV in children in accordance with the STIKO recommendations, as long as no contraindication is evident.

Concepts: Vaccine, Age, Demography, Influenza, Influenza vaccine, Live attenuated influenza vaccine, Vaccines, Influenza vaccines

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Evidence of high efficacy of live attenuated influenza vaccine (LAIV) from randomized controlled trials is strong for children 2-6 years of age, but fewer data exist for older school-age children. We reviewed the published data on efficacy and effectiveness of LAIV in children ≥5 years. QUOSA (Elsevier database) was searched for articles published from January 1990 to June 2014 that included ‘FluMist’, ‘LAIV’, ‘CAIV’, ‘cold adapted influenza vaccine’, ‘live attenuated influenza vaccine’, ‘live attenuated cold adapted’ or ‘flu mist’. Studies evaluated included randomized controlled trials, effectiveness and indirect protection studies. This review demonstrates that LAIV has considerable efficacy and effectiveness in school-age children.

Concepts: Vaccine, Randomized controlled trial, Influenza, Influenza vaccine, 2009 flu pandemic, Live attenuated influenza vaccine, Vaccines, Influenza vaccines

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A postmarketing observational study was initiated to evaluate quadrivalent live attenuated influenza vaccine (LAIV) effectiveness in children aged 2-17 years in the United States.

Concepts: Vaccine, United States, Influenza, Poverty in the United States, U.S. state, Influenza vaccine, Live attenuated influenza vaccine, Influenza vaccines

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Cold-adapted influenza strains A/Leningrad/134/17/57 (H2N2) and B/USSR/60/69, originally developed in Russia, have been reliable master donors of attenuation for preparing live attenuated influenza vaccines (LAIV). The classical strategy for generating LAIV reassortants is robust, but has some disadvantages. The generation of reassortants requires at least 3 passages under selective conditions after co-infection; each of these selective passages takes six days. Screening the reassortants for a genomic composition traditionally starts after a second limiting dilution cloning procedure, and the number of suitable reassortants is limited. We developed a new approach to shorten process of preparing LAIV seed viruses. Introducing the genotyping of reassortants by pyrosequencing and monitoring sequence integrity of surface antigens starting at the first selective passage allowed specific selection of suitable reassortants for the next cloning procedure and also eliminate one of the group selective passage in vaccine candidate generation. Homogeneity analysis confirmed that reducing the number of selective passages didn’t affect the quality of LAIV seed viruses. Finally, the two-way hemagglutination inhibition test, implemented for all the final seed viruses, confirmed that any amino acid substitutions acquired by reassortants during egg propagation didn’t affect antigenicity of the vaccine. Our new strategy reduces the time required to generate a vaccine and was used to generate seasonal LAIVs candidates for the 2012/2013, 2014/2015, and 2015/2016 seasons more rapidly.

Concepts: Vaccine, Vaccination, Influenza, Avian influenza, Influenza vaccine, Live attenuated influenza vaccine, Vaccines, Influenza vaccines