SARS-CoV-2 seroprevalence among firefighters in Los Angeles, California.

OBJECTIVE: We estimate the seroprevalence of SARS-CoV-2 antibodies among a sample of firefighters in the Los Angeles (LA), California fire department in October 2020 and compare demographic and contextual factors for seropositivity. METHODS: We conducted a serological survey of firefighters in LA, California, USA, in October 2020. Individuals were classified as seropositive for SARS-CoV-2 if they tested positive for IgG, IgM or both. We compared demographic and contextual factors for seropositivity. RESULTS: All firefighters in LA, California, USA were invited to participate in our study, but only roughly 21% participated. Of 713 participants with valid serological data, 8.8% tested positive for SARS-CoV-2 antibodies, and among the 686 with complete survey data 8.9% tested positive for antibodies. Seropositivity was not associated with gender, age or race/ethnicity. Seropositivity was highest among firefighters who reported working in the vicinity of LA International Airport, which had a known outbreak in July 2020. CONCLUSIONS: Seroprevalence among firefighters in our sample was 8.8%, however, we lack a full workplace seroprevalence estimate to compare the relative magnitude against general population seroprevalence (15%). Workplace safety protocols, such as access to personal protective equipment and testing, can mitigate increased risk of infection at work, and may have eliminated differences in disease burden by geography and race/ethnicity in our sample.

The relationship of large city out-of-hospital cardiac arrests and the prevalence of COVID-19.

BACKGROUND: Though variable, many major metropolitan cities reported profound and unprecedented increases in out-of-hospital cardiac arrest (OHCA) in early 2020. This study examined the relative magnitude of those increases and their relationship to COVID-19 prevalence. METHODS: EMS (9-1-1 system) medical directors for 50 of the largest U.S. cities agreed to provide the aggregate, de-identified, pre-existing monthly tallies of OHCA among adults (age >18 years) occurring between January and June 2020 within their respective jurisdictions. Identical comparison data were also provided for corresponding time periods in 2018 and 2019.  Equivalent data were obtained from the largest cities in Italy, United Kingdom and France, as well as Perth, Australia and Auckland, New Zealand. FINDINGS: Significant OHCA escalations generally paralleled local prevalence of COVID-19. During April, most U.S. cities (34/50) had >20% increases in OHCA versus 2018-2019 which reflected high local COVID-19 prevalence. Thirteen observed 1·5-fold increases in OHCA and three COVID-19 epicenters had >100% increases (2·5-fold in New York City). Conversely, cities with lesser COVID-19 impact observed unchanged (or even diminished) OHCA numbers. Altogether (n = 50), on average, OHCA cases/city rose 59% during April (p = 0·03). By June, however, after mitigating COVID-19 spread, cities with the highest OHCA escalations returned to (or approached) pre-COVID OHCA numbers while cities minimally affected by COVID-19 during April (and not experiencing OHCA increases), then had marked OHCA escalations when COVID-19 began to surge locally. European, Australian, and New Zealand cities mirrored the U.S. experience. INTERPRETATION: Most metropolitan cities experienced profound escalations of OHCA generally paralleling local prevalence of COVID-19.  Most of these patients were pronounced dead without COVID-19 testing. FUNDING: No funding was involved. Cities provided de-identified aggregate data collected routinely for standard quality assurance functions.