Browsing by Author "Bella, A."
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- Low and decreasing vaccine effectiveness against influenza A(H3) in 2011/12 among vaccination target groups in Europe: results from the I-MOVE multicentre case-control studyPublication . Kissling, E.; Valenciano, M.; Larrauri, A.; Oroszi, B.; Cohen, J.M.; Nunes, Baltazar; Pitigoi, D.; Rizzo, C.; Rebolledo, J.; Paradowska-Stankiewicz, I.; Jiménez-Jorge, S.; Horváth, J.K.; Daviaud, I.; Guiomar, Raquel; Necula, G.; Bella, A.; O'Donnell, J.; Głuchowska, M.; Ciancio, B.C.; Nicoll, A.; Moren, A.Within the Influenza Monitoring Vaccine Effectiveness in Europe (I-MOVE) project we conducted a multicentre case–control study in eight European Union (EU) Member States to estimate the 2011/12 influenza vaccine effectiveness against medically attended influenza-like illness (ILI) laboratory-confirmed as influenza A(H3) among the vaccination target groups. Practitioners systematically selected ILI / acute respiratory infection patients to swab within seven days of symptom onset. We restricted the study population to those meeting the EU ILI case definition and compared influenza A(H3) positive to influenza laboratory-negative patients. We used logistic regression with study site as fixed effect and calculated adjusted influenza vaccine effectiveness (IVE), controlling for potential confounders (age group, sex, month of symptom onset, chronic diseases and related hospitalisations, number of practitioner visits in the previous year). Adjusted IVE was 25% (95% confidence intervals (CI): -6 to 47) among all ages (n=1,014), 63% (95% CI: 26 to 82) in adults aged between 15 and 59 years and 15% (95% CI: -33 to 46) among those aged 60 years and above. Adjusted IVE was 38% (95%CI: -8 to 65) in the early influenza season (up to week 6 of 2012) and -1% (95% CI: -60 to 37) in the late phase. The results suggested a low adjusted IVE in 2011/12. The lower IVE in the late season could be due to virus changes through the season or waning immunity. Virological surveillance should be enhanced to quantify change over time and understand its relation with duration of immunological protection. Seasonal influenza vaccines should be improved to achieve acceptable levels of protection.
- National immunization strategies targeting migrants in six European countriesPublication . Giambi, C.; Del Manso, M.; Dalla Zuanna, T.; Riccardo, F.; Bella, A.; Caporali, M.; Baka, A.; Čakš Jager, N.; Melillo, T.; Mexia, R.; Petrović, G.; Declich, S.; CARE working group for the National Immunization SurveyIntroduction: Over the last three years an unprecedented flow of migrants has arrived in Europe. In hosting countries, immunization strategies targeting migrants are needed to prevent outbreaks of vaccine preventable diseases that could result from lower immunization coverage, bad conditions during the journey and overcrowding of holding centres.
- Temporal Patterns of Influenza A and B in Tropical and Temperate Countries: What Are the Lessons for Influenza Vaccination?Publication . Caini, S.; Andrade, W.; Badur, S.; Balmaseda, A.; Barakat, A.; Bella, A.; Bimohuen, A.; Brammer, L.; Bresee, J.; Bruno, A.; Castillo, L.; Ciblak, M.A.; Clara, A.W.; Cohen, C.; Daouda, C.; de Lozano, C.; De Mora, D.; Dorji, K.; Emukule, G.O.; Fasce, R.A.; Feng, L.; Ferreira de Almeida, W.A.; Guiomar, R.; Heraud, J.M.; Holubka, O.; Huang, Q.S.; Kadjo, H.A.; Kiyanbekova, L.; Kosasih, H.; Kusznierz, G.; Lee, V.; Lara, J.; Li, M.; Lopez, L.; Mai, H.P.; Pessanha, H.C.; Matute, M.L.; Mironenko, A.; Moreno, B.; Mott, J.A.; Njouom, R.; Nurhayati; Ospanova, A.; Owen, R.; Pebody, R.; Pennington, K.; Puzelli, S.; Quynh, Le M.T.; Razanajatovo, N.H.; Rodrigues, A.; Rudi, J.M.; Venter, M.; Vernet, M.A.; Wei, A.L.; Wangchuk, S.; Yang, J.; Yu, H.; Zambon, M.; Schellevis, F.; Paget, J.; Global Influenza B StudyIntroduction: Determining the optimal time to vaccinate is important for influenza vaccination programmes. Here, we assessed the temporal characteristics of influenza epidemics in the Northern and Southern hemispheres and in the tropics, and discuss their implications for vaccination programmes. Methods: This was a retrospective analysis of surveillance data between 2000 and 2014 from the Global Influenza B Study database. The seasonal peak of influenza was defined as the week with the most reported cases (overall, A, and B) in the season. The duration of seasonal activity was assessed using the maximum proportion of influenza cases during three consecutive months and the minimum number of months with 80% of cases in the season. We also assessed whether co-circulation of A and B virus types affected the duration of influenza epidemics. Results: 212 influenza seasons and 571,907 cases were included from 30 countries. In tropical countries, the seasonal influenza activity lasted longer and the peaks of influenza A and B coincided less frequently than in temperate countries. Temporal characteristics of influenza epidemics were heterogeneous in the tropics, with distinct seasonal epidemics observed only in some countries. Seasons with co-circulation of influenza A and B were longer than influenza A seasons, especially in the tropics. Discussion: Our findings show that influenza seasonality is less well defined in the tropics than in temperate regions. This has important implications for vaccination programmes in these countries. High-quality influenza surveillance systems are needed in the tropics to enable decisions about when to vaccinate.