Examination of SARS-CoV-2 serological test results from multiple commercial and laboratory platforms with an in-house serum panel.

Severe acute respiratory syndrome (SARS) coronavirus 2 (SARS-CoV-2) is a novel human coronavirus that was identified in 2019. SARS-CoV-2 infection results in an acute, severe respiratory disease called coronavirus disease 2019 (COVID-19). The emergence and rapid spread of SARS-CoV-2 has led to a global public health crisis, which continues to affect populations across the globe. Real time reverse transcription polymerase chain reaction (rRT-PCR) is the reference standard test for COVID-19 diagnosis. Serological tests are valuable tools for serosurveillance programs and establishing correlates of protection from disease. This study evaluated the performance of one in-house enzyme linked immunosorbent assay (ELISA) utilizing the pre-fusion stabilized ectodomain of SARS-CoV-2 spike (S), two commercially available chemiluminescence assays Ortho VITROS Immunodiagnostic Products Anti-SARS-CoV-2 Total Reagent Pack and Abbott SARS-CoV-2 IgG assay and one commercially available Surrogate Virus Neutralization Test (sVNT), GenScript USA Inc., cPass SARS-CoV-2 Neutralization Antibody Detection Kit for the detection of SARS-CoV-2 specific antibodies. Using a panel of rRT-PCR confirmed COVID-19 patients' sera and a negative control group as a reference standard, all three immunoassays demonstrated high comparable positivity rates and low discordant rates. All three immunoassays were highly sensitive with estimated sensitivities ranging from 95.4-96.6 %. ROC curve analysis indicated that all three immunoassays had high diagnostic accuracies with area under the curve (AUC) values ranging from 0.9698 to 0.9807. High positive correlation was demonstrated among the conventional microneutralization test (MNT) titers and the sVNT inhibition percent values. Our study indicates that independent evaluations are necessary to optimize the overall utility and the interpretation of the results of serological tests. Overall, we demonstrate that all serological tests evaluated in this study are suitable for the detection of SARS-CoV-2 antibodies.

Effects of anti-tau immunotherapy on reactive microgliosis, cerebral endotheliopathy, and cognitive function in an experimental model of cerebral malaria.

Cerebral malaria (CM), a potentially fatal encephalopathy caused primarily by infection with Plasmodium falciparum, results in long-term adverse neuro-psychiatric sequelae. Neural cell injury contributes to the neurological deficits observed in CM. Abnormal regulation of tau, an axonal protein pathologically associated with the formation of neurofibrillary lesions in neurodegenerative diseases, has been linked to inflammation and cerebral microvascular compromise and has been reported in human and experimental CM (ECM). Immunotherapy with a monoclonal antibody to pathological tau (PHF-1 mAB) in experimental models of neurodegenerative diseases has been reported to mitigate cognitive decline. We investigated whether immunotherapy with PHF-1 mAB prevented cerebral endotheliopathy, neural cell injury, and neuroinflammation during ECM. Using C57BL/6 mice infected with either Plasmodium berghei ANKA (PbA), which causes ECM, Plasmodium berghei NK65 (PbN), which causes severe malaria, but not ECM, or uninfected mice (Un), we demonstrated that when compared to PbN infection or uninfected mice, PbA infection resulted in significant memory impairment at 6 days post-infection, in association with abnormal tau phosphorylation at Ser202 /Thr205 (pSer202 /Thr205 ) and Ser396-404 (pSer396-404 ) in mouse brains. ECM also resulted in significantly higher expression of inflammatory markers, in microvascular congestion, and glial cell activation. Treatment with PHF-1 mAB prevented PbA-induced cognitive impairment and was associated with significantly less vascular congestion, neuroinflammation, and neural cell activation in mice with ECM. These findings suggest that abnormal regulation of tau protein contributes to cerebral vasculopathy and is critical in the pathogenesis of neural cell injury during CM. Tau-targeted therapies may ameliorate the neural cell damage and subsequent neurocognitive impairment that occur during disease.

Paediatric acute hepatitis of unknown aetiology: a national surveillance investigation in the USA during 2021 and 2022.

BACKGROUND: Adenovirus is a known cause of hepatitis in immunocompromised children, but not in immunocompetent children. In April, 2022, following multiple reports of hepatitis of unknown aetiology and adenovirus viraemia in immunocompetent children in the USA and UK, the US Centers for Disease Control and Prevention (CDC) and jurisdictional health departments initiated national surveillance of paediatric acute hepatitis of unknown aetiology. We aimed to describe the clinical and epidemiological characteristics of children identified with hepatitis of unknown aetiology between Oct 1, 2021, and Sept 30, 2022, in the USA and to compare characteristics of those who tested positive for adenovirus with those who tested negative. METHODS: In this national surveillance investigation in the USA, children were identified for investigation if they were younger than 10 years with elevated liver transaminases (>500 U/L) who had an unknown cause for their hepatitis and onset on or after Oct 1, 2021. We reviewed medical chart abstractions, which included data on demographics, underlying health conditions, signs and symptoms of illness, laboratory results, vaccination history, radiological and liver pathology findings, diagnoses and treatment received, and outcomes. Caregiver interviews were done to obtain information on symptoms and health-care utilisation for the hepatitis illness, medical history, illness in close contacts or at school or daycare, diet, travel, and other potential exposures. Blood, stool, respiratory, and tissue specimens were evaluated according to clinician discretion and available specimens were submitted to CDC for additional laboratory testing or pathology evaluation. FINDINGS: Surveillance identified 377 patients from 45 US jurisdictions with hepatitis of unknown aetiology with onset from Oct 1, 2021, to Sept 30, 2022. The median age of patients was 2·8 years (IQR 1·2-5·0) and 192 (51%) were male, 184 (49%) were female, and one patient had sex unknown. Only 22 (6%) patients had a notable predisposing underlying condition. 347 patients (92%) were admitted to hospital, 21 (6%) subsequently received a liver transplant, and nine (2%) died. Among the 318 patients without notable underlying conditions, 275 were tested for adenovirus. Of these 116 (42%) had at least one positive specimen, and species F type 41 was the most frequent type identified (19 [73%] of 26 typed specimens were HAdV-41). Proportions of patients who had acute liver failure, received a liver transplant, and died were similar between those who tested positive for adenovirus compared with those who tested negative. Adenovirus species F was detected by polymerase chain reaction in nine pathology liver evaluations, but not by immunohistochemistry in seven of the nine with adequate liver tissue available. Interviews with caregivers yielded no common exposures. INTERPRETATION: Adenovirus, alone or in combination with other factors, might play a potential role in acute hepatitis among immunocompetent children identified in this investigation, but the pathophysiologic mechanism of liver injury is unclear. To inform both prevention and intervention measures, more research is warranted to determine if and how adenovirus might contribute to hepatitis risk and the potential roles of other pathogens and host factors. FUNDING: None.

Clinical and Educational Training About Diversity, Equity, Inclusion, and Justice for Pediatric Residents.

Education and clinical training about diversity, equity, inclusion, and justice (DEIJ) is essential for the personal and professional development of pediatric residents in preparation for a career providing health care to diverse pediatric populations. The ability of pediatric residents to reflect on their lived experiences while gaining perspectives about their patients has the potential to positively affect the health care of patients and decrease health inequities. Clinical rotations were established for students from underrepresented populations in medicine as a pathway for matching and diversifying pediatric residency programs with the potential to help diversify the pediatric workforce. The Accreditation Council for Graduate Medical Education formulated standards about DEIJ in pediatric residency training. Curricula, internships, and mentoring programs have been created by medical institutions and professional medical organizations to provide learning experiences about DEIJ and foster a sense of belonging. This review article highlights the multifactorial approach needed to achieve the goal of diversifying the pediatric workforce through DEIJ instruction in pediatric residency training. [Pediatr Ann. 2023;52(7):e256-e260.].

Longitudinal serologic and viral testing post-SARS-CoV-2 infection and post-receipt of mRNA COVID-19 vaccine in a nursing home cohort-Georgia, October 2020‒April 2021.

There are limited data describing SARS-CoV-2-specific immune responses and their durability following infection and vaccination in nursing home residents. We conducted a prospective longitudinal evaluation of 11 consenting SARS-CoV-2-positive nursing home residents to evaluate the quantitative titers and durability of binding antibodies detected after SARS-CoV-2 infection and subsequent COVID-19 vaccination. The evaluation included nine visits over 150 days from October 25, 2020, through April 1, 2021. Visits included questionnaire administration, blood collection for serology, and paired anterior nasal specimen collection for testing by BinaxNOW™ COVID-19 Ag Card (BinaxNOW), reverse transcription polymerase chain reaction (RT-PCR), and viral culture. We evaluated quantitative titers of binding SARS-CoV-2 antibodies post-infection and post-vaccination (beginning after the first dose of the primary series). The median age among participants was 74 years; one participant was immunocompromised. Of 10 participants with post-infection serology results, 9 (90%) had detectable Pan-Ig, IgG, and IgA antibodies, and 8 (80%) had detectable IgM antibodies. At first antibody detection post-infection, two-thirds (6/9, 67%) of participants were RT-PCR-positive, but none were culture- positive. Ten participants received vaccination; all had detectable Pan-Ig, IgG, and IgA antibodies through their final observation ≤90 days post-first dose. Post-vaccination geometric means of IgG titers were 10-200-fold higher than post-infection. Nursing home residents in this cohort mounted robust immune responses to SARS-CoV-2 post-infection and post-vaccination. The augmented antibody responses post-vaccination are potential indicators of enhanced protection that vaccination may confer on previously infected nursing home residents.

Examination of Common Coronavirus Antibodies in SARS-CoV-2-Infected and Uninfected Participants in a Household Transmission Investigation.

We compared paired serum specimens from household contacts of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cases with detectable SARS-CoV-2 seroconversion with contacts who remained seronegative. No protection from SARS-CoV-2 infection was associated with human coronavirus antibodies; however, an increase in common betacoronavirus antibodies was associated with seroconversion to SARS-CoV-2 in mild to moderately ill cases.

Black Lives Matter: Moving from passion to action in academic medical institutions.

The year 2020 opened the eyes of many to the structures of racism that persist in our country. As the visceral urgency of those galvanizing moments fade, organizations must move beyond releasing supportive statements and determining how they can live up to their stated values. To truly support Black lives, academic medical centers (AMCs) must commit to critically examine and improve the manner in which daily practices, culture, and context uplift Black students, health care professionals, and patients to achieve health equity. One step is to create a culture that is willing to listen and improve when people express discomfort or report mistreatment in order to retain people who are underrepresented in medicine (URiM) in a welcoming environment. Academic centers should address microaggressions to create a safe work and learning atmosphere. Then, ensure that faculty, trainees, and staff represent the demographics of the communities in which institutions are situated. Recruiting and retaining an inclusive health care workforce must be systematic and intentional to achieve representation. Studies have shown that racial and ethnic concordance between providers and patients improves patient satisfaction and health outcomes. Further, business studies have shown that racially diverse leadership teams outperform teams that are more homogenous. Diversity benefits colleagues, learners, and patients by considering different perspectives and improving problem solving. Additionally, AMCss should teach about structural racism as a social determinant of health to raise awareness of a common cause of health disparities and understand why patients of color may distrust the medical system. Furthermore, academic centers should work with local leaders to assess needs and provide community benefits and advocate for policies that meet those needs. While there are some challenges in starting these conversations in our institutions, changing the status quo is necessary to achieve health equity for all.

Comparison of the SARS-CoV-2 spike protein ELISA and the Abbott Architect SARS-CoV-2 IgG nucleocapsid protein assays for detection of antibodies.

Serologic assays developed for SARS-CoV-2 detect different antibody subtypes and are based on different target antigens. Comparison of the performance of a SARS-CoV-2 Spike-Protein ELISA and the nucleocapsid-based Abbott ArchitectTM SARS-CoV-2 IgG assay indicated that the assays had high concordance, with rare paired discordant tests results.

Seroprevalence of SARS-CoV-2 antibodies in Seattle, Washington: October 2019-April 2020.

BACKGROUND: The first US case of SARS-CoV-2 infection was detected on January 20, 2020. However, some serology studies suggest SARS-CoV-2 may have been present in the United States prior to that, as early as December 2019. The extent of domestic COVID-19 detection prior to 2020 has not been well-characterized. OBJECTIVES: To estimate the prevalence of SARS-CoV-2 antibody among healthcare users in the greater Seattle, Washington area from October 2019 through early April 2020. STUDY DESIGN: We tested residual samples from 766 Seattle-area adults for SARS-CoV-2 antibodies utilizing an ELISA against prefusion-stabilized Spike (S) protein. RESULTS: No antibody-positive samples were found between October 2, 2019 and March 13, 2020. Prevalence rose to 1.2% in late March and early April 2020. CONCLUSIONS: The absence of SARS-CoV-2 antibody-positive samples in October 2019 through mid-March, 2020, provides evidence against widespread circulation of COVID-19 among healthcare users in the Seattle area during that time. A small proportion of this metropolitan-area cohort had been infected with SARS-CoV-2 by spring of 2020.

Performance Evaluation of Serial SARS-CoV-2 Rapid Antigen Testing During a Nursing Home Outbreak.

BACKGROUND: To address high COVID-19 burden in U.S. nursing homes, rapid SARS-CoV-2 antigen tests have been widely distributed in those facilities. However, performance data are lacking, especially in asymptomatic people. OBJECTIVE: To evaluate the performance of SARS-CoV-2 antigen testing when used for facility-wide testing during a nursing home outbreak. DESIGN: A prospective evaluation involving 3 facility-wide rounds of testing where paired respiratory specimens were collected to evaluate the performance of the BinaxNOW antigen test compared with virus culture and real-time reverse transcription polymerase chain reaction (RT-PCR). Early and late infection were defined using changes in RT-PCR cycle threshold values and prior test results. SETTING: A nursing home with an ongoing SARS-CoV-2 outbreak. PARTICIPANTS: 532 paired specimens collected from 234 available residents and staff. MEASUREMENTS: Percentage of positive agreement (PPA) and percentage of negative agreement (PNA) for BinaxNOW compared with RT-PCR and virus culture. RESULTS: BinaxNOW PPA with virus culture, used for detection of replication-competent virus, was 95%. However, the overall PPA of antigen testing with RT-PCR was 69%, and PNA was 98%. When only the first positive test result was analyzed for each participant, PPA of antigen testing with RT-PCR was 82% among 45 symptomatic people and 52% among 343 asymptomatic people. Compared with RT-PCR and virus culture, the BinaxNOW test performed well in early infection (86% and 95%, respectively) and poorly in late infection (51% and no recovered virus, respectively). LIMITATION: Accurate symptom ascertainment was challenging in nursing home residents; test performance may not be representative of testing done by nonlaboratory staff. CONCLUSION: Despite lower positive agreement compared with RT-PCR, antigen test positivity had higher agreement with shedding of replication-competent virus. These results suggest that antigen testing could be a useful tool to rapidly identify contagious people at risk for transmitting SARS-CoV-2 during nascent outbreaks and help reduce COVID-19 burden in nursing homes. PRIMARY FUNDING SOURCE: None.

Low SARS-CoV-2 Transmission in Elementary Schools - Salt Lake County, Utah, December 3, 2020-January 31, 2021.

School closures affected more than 55 million students across the United States when implemented as a strategy to prevent the transmission of SARS-CoV-2, the virus that causes COVID-19 (1). Reopening schools requires balancing the risks for SARS-CoV-2 infection to students and staff members against the benefits of in-person learning (2). During December 3, 2020-January 31, 2021, CDC investigated SARS-CoV-2 transmission in 20 elementary schools (kindergarten through grade 6) that had reopened in Salt Lake County, Utah. The 7-day cumulative number of new COVID-19 cases in Salt Lake County during this time ranged from 290 to 670 cases per 100,000 persons.† Susceptible§ school contacts¶ (students and staff members exposed to SARS-CoV-2 in school) of 51 index patients** (40 students and 11 staff members) were offered SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) testing. Among 1,041 susceptible school contacts, 735 (70.6%) were tested, and five of 12 cases identified were classified as school-associated; the secondary attack rate among tested susceptible school contacts was 0.7%. Mask use among students was high (86%), and the median distance between students' seats in classrooms was 3 ft. Despite high community incidence and an inability to maintain ≥6 ft of distance between students at all times, SARS-CoV-2 transmission was low in these elementary schools. The results from this investigation add to the increasing evidence that in-person learning can be achieved with minimal SARS-CoV-2 transmission risk when multiple measures to prevent transmission are implemented (3,4).

Seroprevalence of SARS-CoV-2 Among Frontline Healthcare Personnel During the First Month of Caring for Patients With COVID-19-Nashville, Tennessee.

Among 249 healthcare personnel who worked in hospital units with COVID-19 patients for 1 month, 19 (7.6%) tested positive for SARS-CoV-2 antibodies. Only 11 (57.9%) of the 19 personnel with positive serology reported symptoms of a prior illness, suggesting asymptomatic healthcare personnel could be an important source of SARS-CoV-2 transmission.

Symptoms and Transmission of SARS-CoV-2 Among Children - Utah and Wisconsin, March-May 2020.

BACKGROUND AND OBJECTIVES: Limited data exist on severe acute respiratory syndrome coronavirus 2 in children. We described infection rates and symptom profiles among pediatric household contacts of individuals with coronavirus disease 2019. METHODS: We enrolled individuals with coronavirus disease 2019 and their household contacts, assessed daily symptoms prospectively for 14 days, and obtained specimens for severe acute respiratory syndrome coronavirus 2 real-time reverse transcription polymerase chain reaction and serology testing. Among pediatric contacts (<18 years), we described transmission, assessed the risk factors for infection, and calculated symptom positive and negative predictive values. We compared secondary infection rates and symptoms between pediatric and adult contacts using generalized estimating equations. RESULTS: Among 58 households, 188 contacts were enrolled (120 adults; 68 children). Secondary infection rates for adults (30%) and children (28%) were similar. Among households with potential for transmission from children, child-to-adult transmission may have occurred in 2 of 10 (20%), and child-to-child transmission may have occurred in 1 of 6 (17%). Pediatric case patients most commonly reported headache (79%), sore throat (68%), and rhinorrhea (68%); symptoms had low positive predictive values, except measured fever (100%; 95% confidence interval [CI]: 44% to 100%). Compared with symptomatic adults, children were less likely to report cough (odds ratio [OR]: 0.15; 95% CI: 0.04 to 0.57), loss of taste (OR: 0.21; 95% CI: 0.06 to 0.74), and loss of smell (OR: 0.29; 95% CI: 0.09 to 0.96) and more likely to report sore throat (OR: 3.4; 95% CI: 1.04 to 11.18). CONCLUSIONS: Children and adults had similar secondary infection rates, but children generally had less frequent and severe symptoms. In two states early in the pandemic, we observed possible transmission from children in approximately one-fifth of households with potential to observe such transmission patterns.

A Prospective Cohort Study in Nonhospitalized Household Contacts With Severe Acute Respiratory Syndrome Coronavirus 2 Infection: Symptom Profiles and Symptom Change Over Time.

BACKGROUND: Improved understanding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spectrum of disease is essential for clinical and public health interventions. There are limited data on mild or asymptomatic infections, but recognition of these individuals is key as they contribute to viral transmission. We describe the symptom profiles from individuals with mild or asymptomatic SARS-CoV-2 infection. METHODS: From 22 March to 22 April 2020 in Wisconsin and Utah, we enrolled and prospectively observed 198 household contacts exposed to SARS-CoV-2. We collected and tested nasopharyngeal specimens by real-time reverse-transcription polymerase chain reaction (rRT-PCR) 2 or more times during a 14-day period. Contacts completed daily symptom diaries. We characterized symptom profiles on the date of first positive rRT-PCR test and described progression of symptoms over time. RESULTS: We identified 47 contacts, median age 24 (3-75) years, with detectable SARS-CoV-2 by rRT-PCR. The most commonly reported symptoms on the day of first positive rRT-PCR test were upper respiratory (n = 32 [68%]) and neurologic (n = 30 [64%]); fever was not commonly reported (n = 9 [19%]). Eight (17%) individuals were asymptomatic at the date of first positive rRT-PCR collection; 2 (4%) had preceding symptoms that resolved and 6 (13%) subsequently developed symptoms. Children less frequently reported lower respiratory symptoms (21%, 60%, and 69% for <18, 18-49, and ≥50 years of age, respectively; P = .03). CONCLUSIONS: Household contacts with laboratory-confirmed SARS-CoV-2 infection reported mild symptoms. When assessed at a single timepoint, several contacts appeared to have asymptomatic infection; however, over time all developed symptoms. These findings are important to inform infection control, contact tracing, and community mitigation strategies.

Serologic Testing of US Blood Donations to Identify Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)-Reactive Antibodies: December 2019-January 2020.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19), was first identified in Wuhan, China, in December 2019, with subsequent worldwide spread. The first US cases were identified in January 2020. METHODS: To determine if SARS-CoV-2-reactive antibodies were present in sera prior to the first identified case in the United States on 19 January 2020, residual archived samples from 7389 routine blood donations collected by the American Red Cross from 13 December 2019 to 17 January 2020 from donors resident in 9 states (California, Connecticut, Iowa, Massachusetts, Michigan, Oregon, Rhode Island, Washington, and Wisconsin) were tested at the Centers for Disease Control and Prevention for anti-SARS-CoV-2 antibodies. Specimens reactive by pan-immunoglobulin (pan-Ig) enzyme-linked immunosorbent assay (ELISA) against the full spike protein were tested by IgG and IgM ELISAs, microneutralization test, Ortho total Ig S1 ELISA, and receptor-binding domain/ACE2 blocking activity assay. RESULTS: Of the 7389 samples, 106 were reactive by pan-Ig. Of these 106 specimens, 90 were available for further testing. Eighty-four of 90 had neutralizing activity, 1 had S1 binding activity, and 1 had receptor-binding domain/ACE2 blocking activity >50%, suggesting the presence of anti-SARS-CoV-2-reactive antibodies. Donations with reactivity occurred in all 9 states. CONCLUSIONS: These findings suggest that SARS-CoV-2 may have been introduced into the United States prior to 19 January 2020.

Household Transmission of Severe Acute Respiratory Syndrome Coronavirus-2 in the United States.

BACKGROUND: The evidence base for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is nascent. We sought to characterize SARS-CoV-2 transmission within US households and estimate the household secondary infection rate (SIR) to inform strategies to reduce transmission. METHODS: We recruited patients with laboratory-confirmed SARS-CoV-2 infection and their household contacts in Utah and Wisconsin during 22 March 2020-25 April 2020. We interviewed patients and all household contacts to obtain demographics and medical histories. At the initial household visit, 14 days later, and when a household contact became newly symptomatic, we collected respiratory swabs from patients and household contacts for testing by SARS-CoV-2 real-time reverse-transcription polymerase chain reaction (rRT-PCR) and sera for SARS-CoV-2 antibodies testing by enzyme-linked immunosorbent assay (ELISA). We estimated SIR and odds ratios (ORs) to assess risk factors for secondary infection, defined by a positive rRT-PCR or ELISA test. RESULTS: Thirty-two (55%) of 58 households secondary infection among household contacts. The SIR was 29% (n = 55/188; 95% confidence interval [CI], 23%-36%) overall, 42% among children (aged <18 years) of the COVID-19 patient and 33% among spouses/partners. Household contacts to COVID-19 patients with immunocompromised conditions and household contacts who themselves had diabetes mellitus had increased odds of infection with ORs 15.9 (95% CI, 2.4-106.9) and 7.1 (95% CI: 1.2-42.5), respectively. CONCLUSIONS: We found substantial evidence of secondary infections among household contacts. People with COVID-19, particularly those with immunocompromising conditions or those with household contacts with diabetes, should take care to promptly self-isolate to prevent household transmission.

Lack of Serologic Evidence of Infection Among Health Care Personnel and Other Contacts of First 2 Confirmed Patients With COVID-19 in Illinois, 2020.

OBJECTIVES: Widespread global transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing coronavirus disease 2019 (COVID-19), continues. Many questions remain about asymptomatic or atypical infections and transmission dynamics. We used comprehensive contact tracing of the first 2 confirmed patients in Illinois with COVID-19 and serologic SARS-CoV-2 antibody testing to determine whether contacts had evidence of undetected COVID-19. METHODS: Contacts were eligible for serologic follow-up if previously tested for COVID-19 during an initial investigation or had greater-risk exposures. Contacts completed a standardized questionnaire during the initial investigation. We classified exposure risk as high, medium, or low based on interactions with 2 index patients and use of personal protective equipment (PPE). Serologic testing used a SARS-CoV-2 spike enzyme-linked immunosorbent assay on serum specimens collected from participants approximately 6 weeks after initial exposure to either index patient. The 2 index patients provided serum specimens throughout their illness. We collected data on demographic, exposure, and epidemiologic characteristics. RESULTS: Of 347 contacts, 110 were eligible for serologic follow-up; 59 (17% of all contacts) enrolled. Of these, 53 (90%) were health care personnel and 6 (10%) were community contacts. Seventeen (29%) reported high-risk exposures, 15 (25%) medium-risk, and 27 (46%) low-risk. No participant had evidence of SARS-CoV-2 antibodies. The 2 index patients had antibodies detected at dilutions >1:6400 within 4 weeks after symptom onset. CONCLUSIONS: In serologic follow-up of the first 2 known patients in Illinois with COVID-19, we found no secondary transmission among tested contacts. Lack of seroconversion among these contacts adds to our understanding of conditions (ie, use of PPE) under which SARS-CoV-2 infections might not result in transmission and demonstrates that SARS-CoV-2 antibody testing is a useful tool to verify epidemiologic findings.

Severe Acute Respiratory Syndrome Coronavirus 2 Prevalence, Seroprevalence, and Exposure among Evacuees from Wuhan, China, 2020.

To determine prevalence of, seroprevalence of, and potential exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among a cohort of evacuees returning to the United States from Wuhan, China, in January 2020, we conducted a cross-sectional study of quarantined evacuees from 1 repatriation flight. Overall, 193 of 195 evacuees completed exposure surveys and submitted upper respiratory or serum specimens or both at arrival in the United States. Nearly all evacuees had taken preventive measures to limit potential exposure while in Wuhan, and none had detectable SARS-CoV-2 in upper respiratory tract specimens, suggesting the absence of asymptomatic respiratory shedding among this group at the time of testing. Evidence of antibodies to SARS-CoV-2 was detected in 1 evacuee, who reported experiencing no symptoms or high-risk exposures in the previous 2 months. These findings demonstrated that this group of evacuees posed a low risk of introducing SARS-CoV-2 to the United States.