Prevalence of SARS-CoV-2 Antibodies in First Responders and Public Safety Personnel

New York City, New York, USA, May-July 2020

Samira Sami; Lara J. Akinbami; Lyle R. Petersen; Addie Crawley; Susan L. Lukacs; Don Weiss; Rebecca A. Henseler; Nga Vuong; Lisa Mackey; Anita Patel; Lisa A. Grohskopf; Beth Maldin Morgenthau; Demetre Daskalakis; Preeti Pathela

Disclosures

Emerging Infectious Diseases. 2021;27(3):796-804. 

In This Article

Discussion

SARS-CoV-2 seroprevalence among public service agencies personnel (22.5%) was similar to the 19.5% seroprevalence estimate for NYC residents during comparative dates.[7] However, seroprevalence varied nearly 4-fold by occupation, ranging from 10.1% in laboratory technicians to 39.2% in correctional staff. Similar to other studies, we found seroprevalence varied by nonoccupational factors such as race or ethnicity, age group, weight status, housing type, residence borough, and exposure to household members with COVID-19 (;[8] J.M. Baker, unpub. data, https://doi.org/10.1101/2020.10.30.20222877). However, even when controlling for these factors, we found that seroprevalence for police and firefighters was close to that of the general population; conversely, correctional staff and EMTs, the occupations with the highest seropositivity in our study, had a seroprevalence twice as high.[7] These populations face unique challenges when working in congregate or uncontrolled settings and would be a critical population for vaccination and other public health efforts to reduce SARS-CoV-2 infection.

Correctional facility workers had the highest seroprevalence of SARS-CoV-2 antibodies, and the odds of seropositivity were more than double for these workers compared with police, a group with a seroprevalence similar to the general population. COVID-19 in congregate settings has spread rapidly because of crowded living conditions and few options for isolation of exposed persons.[9–11] Recent data from mass testing in correctional facilities found SARS-CoV-2 prevalence ranged from 0% to 87%.[12] In New York state, 3,762 COVID-19 cases had been reported among staff of 28 correctional and detention facilities as of September 6, 2020.[13] Such recommendations as grouping persons with laboratory-confirmed infection are crucial to prevent COVID-19 outbreaks in correctional facilities, but additional strategies are needed for settings in which isolating multiple persons infected with SARS-CoV-2 might not be possible.[5,14]

Among healthcare workers, EMTs had a seroprevalence of 38.3% and the strongest association with seropositivity after adjustment. In contrast, other SARS-CoV-2 studies among NYC hospital-based healthcare workers found a seroprevalence ranging from 14% to 27%.[15,16] EMS often occur in uncontrolled, unpredictable environments in which space is limited (e.g., ambulances) and require rapid decisions that might increase employee exposure risk. Although EMTs and paramedics both conduct procedures with a high risk for exposure (e.g., airway management), paramedics had a significantly lower seroprevalence than EMTs.[17] Unmeasured factors, such as level of training, might account for the higher likelihood of seropositivity among EMTs compared with paramedics, who undergo an additional >1,000 training hours.[18]

Other occupations with notably elevated seropositivity included traffic officers, security guards, and emergency dispatchers. Persons in these occupations have frequent and close interactions with the general public or work in environments in which space between coworkers is limited. Conversely, medicolegal death investigators and laboratory technicians, occupations with the lowest seroprevalence, might have less frequent close contact with other persons. Our findings also suggest that infection rates in the workplace might correlate with underlying community transmission, and not all observed associations are consistent with occupational risk. After adjustment, persons who worked or resided in the Bronx or Brooklyn had higher seropositivity compared with persons who worked or lived in Staten Island. This finding aligns with test results reported to the NYC Department of Health and Mental Hygiene, which found higher community seroprevalence in the Bronx (32.2%) and Brooklyn (27.0%) than in Staten Island (19.6%).[1]

Our finding that consistent use of gloves was associated with seropositivity was unexpected. However, among occupations without extensive training in glove use, a paradoxical association with infection has been previously observed: higher infection rates among consistent glove users was caused by cross-contamination and lack of hand hygiene after glove removal.[19–22] PPE use has been demonstrated to be effective among healthcare workers in facility settings, but our study of first responders and public safety personnel in nonfacility settings demonstrates a different pattern, which warrants further investigation.[23] Studies among healthcare workers found improper use of PPE, insufficient training, and perceived inadequacy of supplies increased transmission of other coronaviruses and might explain the higher seroprevalence documented in our study.[24–26] Greater PPE use might be a surrogate for greater exposure to COVID-19 in the workplace. According to the hierarchy of controls, engineering and administrative controls (e.g., isolation and indoor ventilation) are preferred, and PPE should be the last line of defense to protect workers.[27]

Public service personnel exposed to a SARS-CoV-2–positive household member also had higher seropositivity, a finding consistent with another study.[28] This finding indicates the importance of managing exposure risk within households of frontline workers. Another factor to consider in NYC is the high density of living conditions, which was associated with greater likelihood of infection in our study. Even after controlling for occupation and housing type, racial and ethnic minority groups had higher seropositivity than non-Hispanic White workers. This pattern might be explained by unmeasured social disparities, such as lower income status, lack of paid sick leave, and mass transit use, which have been found to be associated with seropositivity among racial and ethnic minority groups in NYC (;[29] D. Carrion, unpub. data, https://doi.org/10.1101/2020.06.02.20120790; K.T.L Sy, unpub. data, https://doi.org/10.1101/2020.05.28.20115949). Mitigation measures should address persons working or residing in areas with high levels of SARS-CoV-2 transmission and racial or ethnic disparities.

Limitations of our study include that it was a convenience sample of public service agency personnel with limited numbers of healthcare professionals; participation ranged from an estimated 11% of ≈11,600 eligible correctional facility personnel to 81% of ≈10,300 fire services personnel. Participation might have been influenced by prior results of testing by reverse transcription PCR, expanded access to free antibody testing in the city, household exposure, and worker availability. Data collection occurred during May 18–July 2, 2020; recall bias could have affected responses for exposures 3 months before the survey. Study participants were also asked to recall PPE use during a wide period, and questions were not designed to measure adaptation to evolving PPE use. Temporality also limits our ability to know whether infection occurred before or after a potential exposure. Despite these limitations, our study provides seroprevalence estimates and factors associated with SARS-CoV-2 infection across a diverse set of occupations for which little data exist.

Nearly 25% of first responders and public safety personnel in our study were infected with SARS-CoV-2 before July 2020. Seroprevalence varied by nearly 4-fold among occupations; correctional staff and EMTs demonstrated highest levels of seropositivity. Other occupations with frequent close contact with the public also had elevated seroprevalence. We did not observe lower seroprevalence levels as expected from self-reported consistent PPE use, possibly because persons with consistent use had higher and more frequent exposure to SARS-CoV-2. Nevertheless, these results have identified high-risk occupations for which enhanced prevention measures including engineering and administrative controls and vaccination are required.

processing....