This week, research updates about COVID-19: the largest trial to date of hydroxychloroquine (https://doi.org/10.1101/2020.04.10.20060558), the first serosurvey results (https://doi.org/10.1101/2020.04.14.20062463), doing telehealth (www.bmj.com/content/368/bmj.m1182), masks (https://doi.org/10.17226/25776), the effect of temperature (https://doi.org/10.1101/2020.04.14.20062463) and viral shedding / infectiousness (https://doi.org/10.1038/s41591-020-0869-5).