ObjectivesFirst responders including firefighters, emergency medical technicians (EMT), paramedics, and police officers are working on the front lines to fight the COVID-19 pandemic and facing a higher risk of infection. This study assessed the seroprevalence among first responders in northeastern Ohio during May-September 2020.MethodsA survey and IgG antibody test against SARS-CoV-2 were offered to University Hospitals Health System affiliated first responder departments.ResultsA total of 3080 first responders with diverse job assignments from more than 400 fire and police departments participated in the study. Among them, 73 (2.4%) were seropositive while only 0.8% had previously positive RT-PCR results. Asymptomatic infection accounts for 46.6% of seropositivity. By occupation, seropositive rates were highest among administration/support staff (3.8%), followed by paramedics (3.0%), EMTs (2.6%), firefighters (2.2%), and police officers (0.8%). Seroprevalence was not associated with self-reported exposure as work exposure rates were: paramedics 48.2%, firefighters 37.1%, EMTs 32.3%, police officers 7.7%, and administration/support staff 4.4%. Self-reported community exposure was strongly correlated with self-reported work exposure rate rather than seroprevalence suggesting a potential impact of risk awareness. Additionally, no significant difference was found among gender or age groups; however, black Americans have a higher positivity rate than other races although they reported lower exposure.ConclusionsDespite the high work-associated exposure rate to SARS-CoV-2 infection, first responders with different roles demonstrated seroprevalence no higher than their administrative/supportive colleagues, which suggests infection control measures are effective in preventing work-related infection.