ABSTRACT
ImportanceAntibody testing is important for understanding patterns of exposure and potential immunity to SARS-CoV-2. Prior data on seroprevalence have been subject to variations in selection of individuals and nature as well as timing of testing in relation to exposures. ObjectiveWe sought to determine the extent of SARS-CoV-2 seroprevalance and the factors associated with seroprevelance across a diverse cohort of healthcare workers. DesignObservational cohort study of healthcare workers, including SARS-CoV-2 serology testing and participant questionaires. ParticipantsA diverse and unselected population of adults (n=6,062) employed in a multi-site healthcare delivery system located in Los Angeles County, including individuals with direct patient contact and others with non-patient-oriented work functions. ExposureExposure and infection with the SARS-CoV-2 virus, as determined by seropositivity. Main OutcomesUsing Bayesian and multi-variate analyses, we estimated seroprevalence and factors associated with seropositivity and antibody titers, including pre-existing demographic and clinical characteristics; potential Covid-19 illness related exposures; and, symptoms consistent with Covid-19 infection. ResultsWe observed a seroprevalence rate of 4.1%, with anosmia as the most prominently associated self-reported symptom in addition to fever, dry cough, anorexia, and myalgias. After adjusting for potential confounders, pre-existing medical conditions were not associated with antibody positivity. However, seroprevalence was associated with younger age, Hispanic ethnicity, and African-American race, as well as presence of either a personal or household member having a prior diagnosis of Covid-19. Importantly, African American race and Hispanic ethnicity were associated with antibody positivity even after adjusting for personal Covid-19 diagnosis status, suggesting the contribution of unmeasured structural or societally factors. Notably, number of people, or children, in the home was not associated with antibody positivity. Conclusion and RelevanceThe demographic factors associated with SARS-CoV-2 seroprevalence among our healthcare workers underscore the importance of exposure sources beyond the workplace. The size and diversity of our study population, combined with robust survey and modeling techniques, provide a vibrant picture of the demographic factors, exposures, and symptoms that can identify individuals with susceptibility as well as potential to mount an immune response to Covid-19. Key PointsO_ST_ABSQuestionC_ST_ABSWhat is the SARS-CoV-2 IgG seroprevalence rate across a large and diverse healthcare worker population, and which clinical, envionrmental, and symptom-based measures are associated with seropositivity? FindingsWe observed a seroprevalence rate of 4.1%. Adjusting for potential confounders, seropositivity was associated with younger age, Hispanic ethnicity, African-American race, and the symptom of anosmia, while not significantly associated with any pre-existing medical conditions. MeaningFactors associated with SARS-CoV-2 seroprevalence among our healthcare workers underscore the importance of exposure sources beyond the workplace.
ABSTRACT
Of individuals with SARS-CoV-2 IgG antibody testing performed, those who contemporaneously experienced a cluster of Covid-19 relevant symptoms in the 1-2 months preceding the antibody assay were more likely to test positive whereas those who experienced the symptom clustering in the prior 3-6 months were more likely to test negative. These findings suggest that antibodies likely wane over a period of months, particularly in relation to the timing of symptoms.
ABSTRACT
BackgroundDespite a paucity of clinical evidence, hydroxychloroquine and azithromycin are being administered widely to patients with verified or suspected COVID-19. Both drugs may increase risk of lethal arrhythmias associated with QT interval prolongation. MethodsWe performed a case series of COVID-19 positive/suspected patients admitted between 2/1/2020 and 4/4/2020 who were treated with azithromycin, hydroxychloroquine or a combination. We evaluated baseline and post-medication QT interval (QTc, Bazetts) using 12-lead ECGs. Critical QTc prolongation was defined as: a) maximum QTc [≥]500 ms (if QRS <120 ms) or QTc [≥]550 (if QRS [≥]120 ms) and b) increased QTc of [≥]60 ms. Tisdale score and Elixhauser comorbidity index were calculated. ResultsOf 490 COVID-19 positive/suspected patients, 314 (64%) received either/both drugs, and 98 (73 COVID-19 positive, 25 suspected) met study criteria (age 62{+/-}17 yrs, 61% male). Azithromycin was prescribed in 28%, hydroxychloroquine in 10%, and both in 62%. Baseline mean QTc was 448{+/-}29 ms and increased to 459{+/-}36ms (p=0.005) with medications. Significant prolongation was observed only in men (18{+/-}43 ms vs -0.2{+/-}28 ms in women, p=0.02). 12% of patients reached critical QTc prolongation. In a multivariable logistic regression, age, sex, Tisdale score, Elixhauser score, and baseline QTc were not associated with critical QTc prolongation (p>0.14). Changes in QTc were highest with the combination compared to either drug, with many-fold greater prolongation with the combination vs. azithromycin alone (17{+/-}39 vs. 0.5{+/-}40 ms, p=0.07). No patients manifested torsades de pointes. ConclusionsOverall, 12% of patients manifested critical QTc interval prolongation, and traditional risk indices failed to flag these patients. With the drug combination, QTc prolongation was several-fold higher compared to azithromycin alone. The balance between uncertain benefit and potential risk when treating COVID-19 patients with these drugs should be carefully assessed prior to use.
