BackgroundWidespread use of lateral flow device (LFD) testing of healthcare workers (HCWs) during the coronavirus disease 2019 (COVID-19) pandemic allowed for rapid diagnosis, informing sickness absence.AimIn winter 2023/24, HCWs' attitudes towards sickness absence based on LFD availability and results were investigated.MethodsWithin the SIREN (SARS-CoV-2 Immunity and Reinfection Evaluation) HCW cohort, participants were randomized into one of four hypothetical scenarios – waking up with fever, cough, runny nose and: (a) LFD unavailable; (b) LFD negative; (c) LFD positive for COVID-19; or (d) LFD positive for influenza. For each scenario, participants were asked if they would attend work, their rationale, when they would return to work, and their attitudes towards LFD use. Proportions were calculated to compare scenarios.FindingsIn total, 5357 participants were included, with similar demographics across scenarios. More than 80% of participants reported that they would stay at home if they were LFD positive for COVID-19 or influenza, 54% reported that they would stay at home if LFD testing was unavailable, and 39% reported that they would stay at home if they were LFD negative. The main reason for not taking leave was concern about increasing their colleagues' workload. For each scenario, most participants reported that they would return to work only when they felt well enough. However, in the COVID-19-positive scenario, a higher proportion of participants reported that they would wait 5 days before returning to work. Eighty-four percent of patients reported that they would use an LFD before going to work if they had influenza-like illness symptoms, regardless of hospital policy.ConclusionThis study demonstrated that LFD results are useful in helping HCWs make decisions on whether or not to attend work if they are symptomatic. LFDs remain an important consideration in managing HCWs' infections, and may reduce transmission of respiratory infections in winter