Antibody evidence of SARS-CoV-2 infection in healthcare workers in the Bronx

La provincia Sancti Spíritus en estos momentos muestra la más alta tasa de incidencia del país con 31 7 por 100 000 habitantes en los últimos 14 días, y acumula 304 casos confirmados de COVID-19 desde el 8 de septiembre La mitad de estos casosse concentra en la capital provincial, y los casos reportados representan 36 4% de las cifras del país durante la última semana Se produjo un incremento de los casos de 42 6% (de 54 a 94) respecto a la semana previa Fallecieron dos pacientes y permanece uno en estado grave Se mantienen dos eventos de transmisión local (ETL) en seguimiento en los municipios Sancti Spíritus y Trinidad, que son los de mayores reportes: la cabecera provincial reportó 74 en la semana y acumula 190 durante el rebrote, mientras que Trinidad, la segunda ciudad en importancia de la provincia, acumula 48 casos

1. Were there demographic differences among antibody-positive healthcare workers?
2. What departments had the highest number of positive antibody tests?
3. What is the prevalence of antibody positivity in symptomatic healthcare workers?
4. How many of the asymptomatic healthcare workers developed antibodies?
5. What is the prevalence of antibodies in those healthcare workers with self-reported positive and negative SARS-CoV-2 PCR tests?
Data were extracted from the electronic medical record and were deidentified for analysis. In total, 1,700 healthcare workers were tested for SARS-CoV-2 IgG antibody between April 28 and May 4, 2020. We analyzed the data by looking at those healthcare workers that had positive antibodies and stratified it based on department, presence or absence of symptoms, and previously reported positive PCR.
Of the 1,700 individuals tested, SARS-CoV-2 IgG antibodies were detected in 327 individuals (19%). Among them, 221 healthcare workers with positive antibodies (67.6%) were women. The mean age of those that tested positive was 44 years (range, 22-73). The percentage of African-American healthcare workers that tested positive for antibodies was 27.2%. This was statistically significant compared to other racial groups that tested positive (P < .05). The highest prevalence (26% presence of IgG) was detected in the emergency department and the behavioral health department ( Table 1). The behavioral health department included the psychiatric emergency room and inpatient and outpatient psychiatry. Suprisingly, the lowest prevalence was found in critical care staff, with 11% testing positive.
More than half (53%) of the individuals tested reported having symptoms suggestive of COVID-19. Of these healthcare workers, 28% showed the presence of IgG antibody, and 9% of asymptomatic healthcare workers had IgG antibodies. Notably, 12% of those who tested positive for the presence of IgG reported a negative SARS-CoV-2 PCR result. As expected, 92% of individuals that reported a positive PCR test developed IgG antibodies. A small number of individuals, representing 1% of those reporting a positive SARS-CoV-2 PCR test prior to being tested, had a negative antibody test. This finding is consistent with a previous report from China in which a small number of patients with COVID-19 did not develop antibodies. 6 Our results reflect a higher overall rate of SARS-CoV-2 antibody development among healthcare workers in the Bronx compared to reported rates in NYC healthcare workers. 3 However, the rates were lower than the reported Bronx community prevalence. 4 This finding is not unexpected because hospital staff had better access to protective equipment than did the general population as well as a heightened awareness of the seriousness of the infection. Based on our findings, hospitals with psychiatric services, especially with psychiatric emergency departments, should consider increasing the use of SARS-CoV-2 transmission prevention resources. Our African-American healthcare workers had a significant difference in antibody positivity. This finding needs to be confirmed in a larger study, and additional investigation is necessary to understand the reasons for this finding. The low rate of antibody development in critical care areas could be explained by the controlled environment and lower volume compared to other areas. Finally, 12% of hospital staff who developed antibodies in spite of a negative PCR test could be explained by false-negative PCR testing, infection after the PCR test, or inaccurate self-report.
It is unclear whether the presence of IgG antibodies confers long-term immunity. Emphasis is being placed on antibody testing for reopening the economy and return-to-work policies. 7,8 However, only 1 in 5 healthcare workers developed antibodies during the peak of the pandemic at our hospital; thus, the utility of antibody testing to guide staffing considerations is limited. Ultimately, development of prophylactic treatments and therapies for COVID-19 is needed to ensure the safety of our healthcare workers pending the arrival of a vaccine.