Letter to the editor: Measles outbreak in Gothenburg urban area, Sweden, 2017 to 2018: low viral load in breakthrough infections Bolotin, Shelly and Crowcroft, Natasha S and Hughes, Stephanie L and De Serres, Gaston, Eurosurveillance, 24, 1900465 (2019), https://doi.org/10.2807/1560-7917.ES.2019.24.30.1900465