The psychological effects of quarantining a city are significant and should not be overlooked when considering the epidemiological benefits. G James Rubin and Simon Wessely, from King's College London, highlight that while mandatory mass quarantine may help control outbreaks, the psychological costs are substantial. The imposition of quarantine, especially on a large scale, can lead to anxiety, fear, and a sense of being trapped. These effects are exacerbated by the lack of clear information, the separation of families, and the spread of rumors. The media often portrays public responses as panic, which can lead to policies that control the population for their own wellbeing, potentially withholding important information. Mass quarantine can also lead to social stigma and discrimination against those in quarantine, as seen in previous outbreaks. The long-term effects may include anger and social disruption, particularly if the outbreak impacts the economy. While quarantine has been a part of public health strategy since the Justinian plague, it is important to consider the psychological side effects and explore alternatives, such as voluntary quarantine, which may have less psychological impact. The authors emphasize that the decision to implement mandatory mass quarantine should not be made lightly, as the uncertain epidemiological benefits must be weighed against the uncertain psychological costs. They are affiliated with the National Institute for Health Research Health Protection Research Unit and have no competing interests. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR, the Department of Health and Social Care, or Public Health England.The psychological effects of quarantining a city are significant and should not be overlooked when considering the epidemiological benefits. G James Rubin and Simon Wessely, from King's College London, highlight that while mandatory mass quarantine may help control outbreaks, the psychological costs are substantial. The imposition of quarantine, especially on a large scale, can lead to anxiety, fear, and a sense of being trapped. These effects are exacerbated by the lack of clear information, the separation of families, and the spread of rumors. The media often portrays public responses as panic, which can lead to policies that control the population for their own wellbeing, potentially withholding important information. Mass quarantine can also lead to social stigma and discrimination against those in quarantine, as seen in previous outbreaks. The long-term effects may include anger and social disruption, particularly if the outbreak impacts the economy. While quarantine has been a part of public health strategy since the Justinian plague, it is important to consider the psychological side effects and explore alternatives, such as voluntary quarantine, which may have less psychological impact. The authors emphasize that the decision to implement mandatory mass quarantine should not be made lightly, as the uncertain epidemiological benefits must be weighed against the uncertain psychological costs. They are affiliated with the National Institute for Health Research Health Protection Research Unit and have no competing interests. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR, the Department of Health and Social Care, or Public Health England.