TY - JOUR AU - Remschmidt, Cornelius AU - Wichmann, Ole AU - Harder, Thomas PY - 2015 DA - 2015/10/17 TI - Frequency and impact of confounding by indication and healthy vaccinee bias in observational studies assessing influenza vaccine effectiveness: a systematic review JO - BMC Infectious Diseases SP - 429 VL - 15 IS - 1 AB - Evidence on influenza vaccine effectiveness (VE) is commonly derived from observational studies. However, these studies are prone to confounding by indication and healthy vaccinee bias. We aimed to systematically investigate these two forms of confounding/bias. SN - 1471-2334 UR - https://doi.org/10.1186/s12879-015-1154-y DO - 10.1186/s12879-015-1154-y ID - Remschmidt2015 ER -