This review covers the thematic series of 22 papers selected from among manuscripts published by BJPsych Open concerning coronavirus disease 2019 (COVID-19) and healthcare. We report nine papers that cover concepts and epidemiology relating to the public and patients. We review 11 papers about the impact of COVID-19 on healthcare services and their staff in 15 countries. Two papers consider the psychosocial impact on staff working in mental health services in the UK. Most papers report cross-sectional analyses of data collected from convenience samples by self-reported surveys conducted at single times. They have limitations of generalisability, do not enable conclusions about diagnosis or causality, and many are likely to have attendant bias and noise. BJPsych Open published these papers to meet requirements for early indications of the mental health impact of COVID-19 on the public and on healthcare staff. They claim high prevalence of symptoms of anxiety, depression and post-traumatic stress. We contrast these findings with selected reports of studies with different methodologies published elsewhere. We emphasise the need for longitudinal clinical studies with refined sampling and methodological rigour. We identify several longitudinal research programmes; two in this series. We advocate tuning advice offered about caring for the public and healthcare staff to the realities of their circumstances and their perceptions of need in the context of findings from further longitudinal studies. We draw attention to the importance of the social, relationship and environmental circumstances of the public and healthcare staff in order to understand their distress and their risks of developing mental health disorders.