Guiomar Raquel, Pereira da Silva Susana, Conde Patrícia, Cristóvão Paula, Maia Ana Carina, Pechirra Pedro, Rodrigues Ana Paula, Nunes Baltazar, Milho Luís, Coelho Ana Paula, Fernandes Aida, Caseiro Paula, Rodrigues Fernando, Correia Lurdes, Pereira-Vaz João, Almeida Sofia, Branquinho Paula, Côrte-Real Rita, Viseu Regina, Peres Maria João, Sanches Raquel, Dantas Filipa, Freitas Ludovina, Andrade Graça, Maurílio Manuel, Caldeira Filomena, Cabral Veloso Rita, Mota-Vieira Luisa, Soares Marta, Couto Ana Rita, Bruges-Armas Jácome, Pinto Rita Mouro, Sobrinho Simões Joana, Costa Maria do Rosário, Guimarães João Tiago, Martins Luís, Cunha Mário
Instituto Nacional de Saúde Doutor Ricardo Jorge, I.P., Portugal.
Administração Regional de Saúde do Algarve, I.P., Laboratório Regional de Saúde Pública Laura Ayres, Portugal.
Vaccine. 2017 Apr 11;35(16):2092-2099. doi: 10.1016/j.vaccine.2017.02.019. Epub 2017 Mar 18.
Immune profile for influenza viruses is highly changeable over time. Serological studies can assess the prevalence of influenza, estimate the risk of infection, highlight asymptomatic infection rate and can also provide data on vaccine coverage. The aims of the study were to evaluate pre-existing cross-protection against influenza A(H3) drift viruses and to assess influenza immunity in the Portuguese population.
We developed a cross-sectional study based on a convenience sample of 626 sera collected during June 2014, covering all age groups, both gender and all administrative health regions of Portugal. Sera antibody titers for seasonal and new A(H3) drift influenza virus were evaluated by hemagglutination inhibition assay (HI). Seroprevalence to each seasonal influenza vaccine strain virus and to the new A(H3) drift circulating strain was estimated by age group, gender and region and compared with seasonal influenza-like illness (ILI) incidence rates before and after the study period.
Our findings suggest that seroprevalences of influenza A(H3) (39.9%; 95% CI: 36.2-43.8) and A(H1)pdm09 (29.7%; 95% CI: 26.3-33.4) antibodies were higher than for influenza B, in line with high ILI incidence rates for A(H3) followed by A(H1)pdm09, during 2013/2014 season. Low pre-existing cross-protection against new A(H3) drift viruses were observed in A(H3) seropositive individuals (46%). Both against influenza A(H1)pdm09 and A(H3) seroprotection was highest in younger than 14-years old. Protective antibodies against influenza B were highest in those older than 65years old, especially for B/Yamagata lineage, 33.3% (95% CI: 25.7-41.9). Women showed a high seroprevalence to influenza, although without statistical significance, when compared to men. A significant decreasing trend in seroprotection from north to south regions of Portugal mainland was observed.
Our results emphasize that low seroprotection increases the risk of influenza infection in the following winter season. Seroepidemiological studies can inform policy makers on the need for vaccination and additional preventive measures.
流感病毒的免疫特征会随时间发生很大变化。血清学研究可以评估流感的流行情况，估计感染风险，突出无症状感染率，还能提供疫苗接种覆盖率的数据。本研究的目的是评估针对甲型（H3）流感病毒变异株的预先存在的交叉保护作用，并评估葡萄牙人群的流感免疫力。
我们开展了一项横断面研究，基于2014年6月收集的626份血清的便利样本，涵盖了葡萄牙所有年龄组、性别以及所有行政区卫生区域。通过血凝抑制试验（HI）评估季节性和新型甲型（H3）流感病毒变异株的血清抗体滴度。按年龄组、性别和地区估算每种季节性流感疫苗株病毒和新型甲型（H3）流感病毒变异株的血清阳性率，并与研究期间前后的季节性流感样疾病（ILI）发病率进行比较。
我们的研究结果表明，甲型（H3）流感（39.9%；95%置信区间：36.2 - 43.8）和甲型（H1）pdm09流感（29.7%；95%置信区间：26.3 - 33.4）抗体的血清阳性率高于乙型流感，这与2013/2014季节甲型（H3）流感随后是甲型（H1）pdm09流感的高ILI发病率一致。在甲型（H3）血清阳性个体中观察到对新型甲型（H3）流感病毒变异株的预先存在的交叉保护作用较低（46%）。针对甲型（H1）pdm09流感和甲型（H3）流感的血清保护作用在14岁以下人群中最高。针对乙型流感的保护性抗体在65岁以上人群中最高，尤其是对于乙型山形系，为33.3%（95%置信区间：25.7 - 41.9）。与男性相比，女性的流感血清阳性率较高，尽管无统计学意义。在葡萄牙大陆从北部到南部地区观察到血清保护作用有显著下降趋势。
我们的结果强调血清保护作用低会增加下一个冬季流感感染的风险。血清流行病学研究可为政策制定者提供有关疫苗接种需求和其他预防措施的信息。
