Background The COVID-19 pandemic has substantially affected mental health but its impacts are likely to differ across industries and social class groups. The ‘new normal’ in employment opportunities, patterns and conditions is likely to include a degree of fear, uncertainty, employment instability and job loss. It is imperative we identify and understand how workers have been disadvantaged by the pandemic and current working modes. We aimed to examine the impact of COVID-19 on the mental health of UK workers by industry and social class category and to investigate whether any observed impacts differed by age, gender, and country of residence within the UK.

Methods We used the UK Household Longitudinal Study (Understanding Society) to analyse data from adults in paid employment, who participated in pre-COVID-19 Waves [9(2017/19) and 10/11(2018/20)] and in at least one COVID-19 wave. Our primary outcome was probable psychological distress, defined by ‘caseness’ (a score of 4+) in the General Health Questionnaire-12 (GHQ-12) and exposures included industrial sectors (classified using the UK Standard Industrial Classification) and social class (using the Eight Class National Statistics Socio-economic Classification). We fitted mixed-effects logistic regression models, adjusting for age, gender, employment type, financial situation and UK country of residence and used inverse probability weights to account for attrition and non-response, to estimate odds ratios (ORs) with 95% confidence intervals (95%CI). Subsequently, we stratified by gender, UK country of residence, and age group.

Results Our final sample includes 44,500 observations (Pre-pandemic period=13,314, pandemic period=31,186) across 7,075 individuals. GHQ-caseness increased for workers in most industries during the pandemic; especially in ‘Accommodation and Food Services’ (OR:3.2; 95%CI:1.9,5.4). Analysis by social class showed that ‘Small employers and own account’ workers were the most affected (OR:2.9; 95%CI:2.1,4.0). Our stratified analysis by industry demonstrated the largest increase in GHQ-caseness between the pre and pandemic periods to be by gender in the ‘Accommodation and Food Services’ sector (OR:9.6; 95%CI:3.2,29.0 for men; OR:2.0; 95%CI:1.2,3.4 for women); whereas by social class the largest increase was observed when stratifying by UK country of residence for ‘Small employers and own account’ workers (non-England: OR:8.8; 95%CI:4.1,18.8; England: OR:2.5; 95%CI:1.6,3.9).

Conclusion Our findings indicate that the pandemic has significantly affected the mental health of UK workers. Policies with a decentralised element are needed, prioritising support to certain industrial sectors and the self-employed/small business owners, as well as for particular demographic groups (e.g. men in the ‘Accommodation and Food Services’ industry) who are in an excessively high risk.