Background: Well-established influenza surveillance systems (ISS) can be used for respiratory syncytial virus (RSV) surveillance. In Portugal, RSV cases are detected through the ISS using the European Union (EU) influenza-like illness (ILI) case definition. Aim: To investigate clinical predictors for RSV infection and how three case definitions (EU ILI, a modified EU acute respiratory infection, and one respiratory symptom) performed in detecting RSV infections in Portugal. Methods: This observational retrospective study used epidemiological and laboratory surveillance data (October 2010–May 2018). Associations between clinical characteristics and RSV detection were analysed using logistic regression. Accuracy of case definitions was assessed through sensitivity, specificity, and area under the receiver operating characteristic curve (AUC). A 0.05 significance level was accepted. Results: The study involved 6,523 persons, including 190 (2.9%) RSV cases. Among 183 cases with age information, RSV infection was significantly more frequent among individuals < 5 years (n = 23; 12.6%) and ≥ 65 years (n = 45; 24.6%) compared with other age groups (p < 0.0001). Cough (odds ratio (OR): 2.4; 95% confidence interval (CI): 1.2–6.5) was the best RSV-infection predictor considering all age groups, while shortness of breath was particularly associated with RSV-positivity among ≤ 14 year olds (OR: 6.7; 95% CI: 2.6–17.4 for 0–4 year olds and OR: 6.7; 95% CI: 1.5–28.8 for 5–14 year olds). Systemic symptoms were significantly associated with RSV-negative and influenza-positive cases. None of the case definitions were suitable to detect RSV infections (AUC = 0.51). Conclusion: To avoid underestimating the RSV disease burden, RSV surveillance within the Portuguese sentinel ISS would require a more sensitive case definition than ILI and, even a different case definition according to age. ; info:eu-repo/semantics/publishedVersion
BACKGROUND: Well-established influenza surveillance systems (ISS) can be used for respiratory syncytial virus (RSV) surveillance. In Portugal, RSV cases are detected through the ISS using the European Union (EU) influenza-like illness (ILI) case definition. AIM: To investigate clinical predictors for RSV infection and how three case definitions (EU ILI, a modified EU acute respiratory infection, and one respiratory symptom) performed in detecting RSV infections in Portugal. METHODS: This observational retrospective study used epidemiological and laboratory surveillance data (October 2010–May 2018). Associations between clinical characteristics and RSV detection were analysed using logistic regression. Accuracy of case definitions was assessed through sensitivity, specificity, and area under the receiver operating characteristic curve (AUC). A 0.05 significance level was accepted. RESULTS: The study involved 6,523 persons, including 190 (2.9%) RSV cases. Among 183 cases with age information, RSV infection was significantly more frequent among individuals < 5 years (n = 23; 12.6%) and ≥ 65 years (n = 45; 24.6%) compared with other age groups (p < 0.0001). Cough (odds ratio (OR): 2.4; 95% confidence interval (CI): 1.2–6.5) was the best RSV-infection predictor considering all age groups, while shortness of breath was particularly associated with RSV-positivity among ≤ 14 year olds (OR: 6.7; 95% CI: 2.6–17.4 for 0–4 year olds and OR: 6.7; 95% CI: 1.5–28.8 for 5–14 year olds). Systemic symptoms were significantly associated with RSV-negative and influenza-positive cases. None of the case definitions were suitable to detect RSV infections (AUC = 0.51). CONCLUSION: To avoid underestimating the RSV disease burden, RSV surveillance within the Portuguese sentinel ISS would require a more sensitive case definition than ILI and, even a different case definition according to age.
This report was prepared as part of the Project "Monitoring Influenza vaccine effectiveness during influenza seasons and pandemics in the European Union" and describes the results obtained in Portugal under the Protocol Agreement celebrated between EpiConcept SARL, Paris and National Health Institute Dr. Ricardo Jorge, Lisbon. Data and activities related to the individuals 65 years and more were funded by European Union's Horizon 2020 research and innovation programme under grant agreement no 634446. ; The results to be presented are related to the 8th EuroEVA season (the Portuguese component of the multicentre I-MOVE study) and aimed the estimation of 2015/2016 end of season influenza vaccine effectiveness in i) all age groups and in <65 and 65 plus years ; ii) by risk group; iii) by influenza subtype and clade. Material and methods: The "Protocol for case-control studies to measure seasonal influenza vaccine effectiveness in the European Union and European Economic Area Member States- Portuguese site study version" was implemented entirely adding a new variable related to statin uptake. Also, a pilot study to incorporate genetic characterization of influenza virus from patients enrolled in vaccine effectiveness (VE) study was implemented. Within this pilot study, influenza A(H1)pdm09 positive cases were randomly selected to be genetically characterized. Selection was conducted in three phases of the epidemic: early, peak and late season. Results: In Portugal, a low intensity influenza epidemic occurred between week 53/2015 and week 8/2016. Influenza A(H1)pdm09 virus predominated during all season. Influenza B/Victoria lineage was detected in co-circulation in late season. From the 84 GP's that accepted to participate in the study, 51 GP's effectively participated in the study selecting patients (60.7% participation rate). A total of 336 ILI patients were enrolled and after excluding 26 ILI patients the final sample for analyses consisted on 310 ILI patients (147 cases and 102 controls). From the cases, 89.5% were positive for influenza A(H1)pdm09, 8.9% were positive for influenza B/Victoria and the remaining (1.6%) were positive for influenza A(H3). For genetic characterization of influenza virus, A(H1)pdm09 virus subtype was selected. The HA1 subunit of the hemaglutinin gene were successfully sequenced for 93 out of 126 cases with detected viruses. Phylogenetic analysis and clade assignment were performed. The majority of A(H1)pdm09 viruses belonged to the subgroup 6B.1 (87.1%) and the remaining viruses belonged to 6B clade. Comparing cases and controls, was confirmed that they were statistically different in relation to time between onset and swab collection, sex, seasonal vaccine uptake in 2014/2015, presence of at least one chronic disease and number of GP consultations in last 12 months. For 2015/2016 trivalent influenza vaccine, confounder- adjusted VE against A(H1)pdm09 was 54.0% (95% CI: -1.5; 79.2%) in all population and 63.9% (95% CI: (7.7%; 85.9%) in the target group for vaccination. Considering the population with less than 65 years, VE against AH1pdm09 was 56.2% (95% CI: -17.5%; 83.7%) and 74.9% (95% CI: -37.1; 95.4%) in the and more years of age. Conclusions: VE estimates during 2015/2016 season indicated that the seasonal flu vaccine conferred moderate protection against A(H1)pdm09 (varied between 54% to 64% considering all population and the target group for vaccination). The vaccine had a better performance in the elderly, where VE point estimates reached 75% (not significant nevertheless). The implementation of the genetic characterization pilot study was well succeeded, with a success rate of influenza virus characterization of 80.2%. For future seasons, the high sampling fraction in the first phase should continue in order to assist the definition of the virus subtype/clade target during the season. ; Os resultados apresentados correspondem à implementação da 8ª época do EuroEVA (a componente portuguesa do estudo multicêntrico I-MOVE) e pretende obter estimativas da efetividade da vacina (EV) sazonal 2015/2016 i) em todos os grupos etários e no grupo com idade inferior a 65 e com 65 e mais anos; ii) por grupo-alvo da vacinação e iii) por subtipo de vírus da gripe e por clade. Material e métodos: O "Protocol for case-control studies to measure seasonal influenza vaccine effectiveness in the European Union and European Economic Area Member States- Portuguese site study version" foi implementado na íntegra, acrescentando um nova variável relacionada com a toma de estatinas. De igual modo, foi implementando um estudo-piloto relacionado com a incorporação da caracterização genética dos participantes no estudo da efetividade. Dentro deste estudo-piloto, os casos positivos de A(H1)pdm09 foram aleatoriamente selecionados para caracterização genética, seleção esta que foi conduzida nas três fases do período epidémico: início, pico e fim. Resultados: Em Portugal o período epidémico ocorreu entre as semanas 53/2015 e 8/2016 tendo-se verificado uma atividade gripal de intensidade baixa. Predominou a circulação de vírus do subtipo Influenza A(H1)pdm09 e o vírus Influenza da linhagem B/Victoria co-circulou no final da época. De entre os 84 médicos de família (MF) que aceitaram participar no estudo, 51 reportaram doentes com síndroma gripal (SG), correspondendo a uma taxa de participação de 60,7%. No total foram selecionados 336 doentes com SG. Após exclusão de 26 doentes, a amostra final consistiu em 310 doentes com SG (147 casos e 102 controlos). De entre os casos, 89,5% eram do subtipo A(H1)pdm2009, 8,9% eram positivos para o vírus do subtipo B/Victoria e os restantes (1,6%) para o tipo A(H3). Para efeito de caracterização genética, o subptipo A(H1)pdm09 foi selecionado. A subunidade HA1 do gene da hemaglutinina foi sequenciada com sucesso para 93 dos 126 casos. A maioria dos casos de A(H1)pdm09 pertencia ao subgrupo 6B.1 (87,1%) e os restantes ao subgrupo 6B. Comparando casos e controlos verifica-se que os grupos eram estatisticamente diferentes no que diz respeito, ao tempo entre início de sintomas e colheita, ao sexo, a toma da vacina na época anterior, à presença de doença crónica relevante para vacinação da gripe e ao número de consultas com o MF nos últimos 12 meses. Para a vacina trivalente antigripal 2015/2016 a EV ajustada para confundimento contra o subtipo A(H1)pdm09 foi 54,0% (IC95%: -1,5; 79,2%) na população em geral e 63,9% (IC95%: (7,7%; 85,9%) no grupo alvo da vacinação contra a gripe. Considerando a população com menos de 65 anos, a EV contra o subtipo A(H1)pdm09 foi de 56,2 % (IC 95%: -17,5%; 83,7%), sendo que foi de 74,9% (IC 95%: -37,1; 95,4%) no grupo com 65 e mais anos de idade. Conclusões: As estimativas da EV da época 2015/2016 indicam que a vacina conferiu proteção moderada contra o subtipo A(H1)pdm09 (variou entre 54% e 64%, para a população em geral e para o grupo alvo da vacina, respetivamente). A vacina parece demonstrar uma melhor performance na população mais idosa, onde as estimativas da EV alcançam os 75% (apesar de não estatisticamente significativas). A implementação do estudo piloto foi bem conseguida, com uma taxa de sucesso de caracterização genética de 80,2%. Em épocas futuras, a amostragem na primeira fase deve manter elevada, de modo a assistir à definição do subtipo/clade do vírus a ser caracterizado.
