Gómez, VerónicaKislaya, IrinaMachado, AusendaPechirra, PedroCosta, InêsCristóvão, PaulaConde, PatríciaGuiomar, RaquelNunes, Baltazar2021-03-122021-03-122020-10http://hdl.handle.net/10400.18/7416Background: The test-negative design (TND) has been used to monitor influenza vaccine effectiveness (IVE). Negative controls are those that tested negative for any influenza virus - however, there are issues related to the selection of the negative controls; As it is hypothesized a potential bias introduced by virus interference in TND, some authors suggest to use other respiratory virus as control group. Hence, the objective of this study is to compare IVE estimates using the classic TND and alternative controls.engGripeVacina AntigripalEfetividadeEstados de Saúde e de DoençaDeterminantes da Saúde e da DoençaEuroEVAOutros Vírus RespiratóriosInfecções RespiratóriasPortugalconference object