The COVID-19 crisis has heightened the risk factors generally associated with poor mental health – financial insecurity, unemployment, fear – while protective factors – social connection, employment and educational engagement, access to physical exercise, daily routine, access to health services – fell dramatically. This has led to a significant and unprecedented worsening of population mental health. Across countries, the mental health of unemployed people and those experiencing financial insecurity was worse than that of the general population – a trend that pre-dates the pandemic, but seems to have accelerated in some cases. OECD countries have responded with decisive efforts to scale-up mental health services, and put into place measures to protect jobs and incomes, thereby reducing mental distress for some. However, the scale of mental distress since the start of the pandemic requires more integrated, whole-of-society mental health support if it is not to lead to permanent scarring.