Assessing the Burden of COVID-19 among Children Aged 6-14 Years in Karnataka, India: A Cross-sectional Survey.

Background: India experienced three coronavirus disease (COVID-19) waves, with the third attributed to the highly contagious Omicron variant. Before the national vaccination rollout for children above 6, understanding severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin G (IgG) positivity in the pediatric population was essential. This study aims to assess the burden of Covid-19 infection and to estimate the seroprevalence in children aged 6 to 14 years in the state of Karnataka. Material and Methods: We surveyed 5,358 children aged 6-14 across Karnataka using 232 health facilities, from June 6 to 14, 2022. We determined the sample size using the PPS (Population Proportional to Size) technique and employed cluster sampling. We tested all participants for SARS-CoV-2 IgG with an enzyme-linked immunosorbent assay (ELISA) kit and SARS-CoV-2 RNA with reverse transcription-polymerase chain reaction (RT-PCR). We sequenced samples with a cycle threshold (CT) value below 25 using whole genomic sequencing (WGS). Result: We found an adjusted seroprevalence of IgG at 75.38% statewide, and we found 0.04% of children RT-PCR positive for COVID-19. We determined a case-to-infection ratio of 1:37 and identified the SARS-CoV-2 strains as Omicron, BA.5, and BA.2.10. Conclusion: The study showed a high seroprevalence of IgG among children with low active infection. Omicron, BA. 5, and BA. 2.10 variants were detected through WGS.

COVID-19 symptoms and antibody positivity among unvaccinated pregnant women: An observational study in seven countries from the Global Network.

OBJECTIVE: To determine the relation of COVID-19 symptoms to COVID-19 antibody positivity among unvaccinated pregnant women in low- and middle-income countries (LMIC). DESIGN: COVID-19 infection status measured by antibody positivity at delivery was compared with the symptoms of COVID-19 in the current pregnancy in a prospective, observational cohort study in seven LMICs. SETTING: The study was conducted among women in the Global Network for Women's and Children's Health's Maternal and Newborn Health Registry (MNHR), a prospective, population-based study in Kenya, Zambia, the Democratic Republic of the Congo (DRC), Bangladesh, Pakistan, India (Belagavi and Nagpur sites) and Guatemala. POPULATION: Pregnant women enrolled in the ongoing pregnancy registry at study sites. METHODS: Data on COVID-19 symptoms during the current pregnancy were collected by trained staff between October 2020 and June 2022. COVID-19 antibody testing was performed on samples collected at delivery. The relation between COVID-19 antibody positivity and symptoms was assessed using generalised linear models with a binomial distribution adjusting for site and symptoms. MAIN OUTCOME MEASURES: COVID-19 antibody status and symptoms of COVID-19 among pregnant women. RESULTS: Among 19 218 non-vaccinated pregnant women who were evaluated, 14.1% of antibody-positive women had one or more symptoms compared with 13.4% in antibody-negative women. Overall, 85.3% of antibody-positive women reported no COVID-19 symptoms during the present pregnancy. Reported fever was significantly associated with antibody status (relative risk [RR] 1.10, 95% CI 1.03-11.18; P = 0.008). A multiple variable model adjusting for site and all eight symptoms during pregnancy showed similar results (RR 1.13, 95% CI 1.04-1.23; P = 0.012). None of the other symptoms was significantly related to antibody positivity. CONCLUSIONS: In a population-based cohort in LMICs, unvaccinated pregnant women who were antibody-positive had slightly more symptoms during their pregnancy and a small but significantly greater increase in fever. However, for prevalence studies, evaluating COVID-19-related symptoms does not appear to be useful in differentiating pregnant women who have had a COVID-19 infection.

Magnetic Resonance Imaging Scan of the Brain After Mild COVID-19 Infection.

PURPOSE: There have been several reports of central nervous system impairments associated with severe coronavirus disease 2019 (COVID-19) infection on head magnetic resonance imaging and angiography (MRI/A). However, head MRI/A is rarely performed in mild cases, and there have been few reports on intracranial changes after COVID-19 infection in these cases. Here, we report a comparative examination of the findings seen in common head MRI/A sequences in mild cases of COVID-19. METHODS: Of the 15,376 patients who underwent head MRI/A examination called "Brain Dock" between June 2020 and June 2021, 746 patients who received a COVID-19 antibody test were evaluated. Positive and negative patients were comparatively examined for head MRI/A findings such as cerebral white matter lesions, ischemic changes, cerebral microbleeds, cerebral aneurysms, arterial stenosis, sinusitis, and other abnormal findings. RESULTS: Overall, 31 (4.2%) patients were COVID-19 positive, and all of them had mild infections not requiring hospitalization. There was no significant difference in patient characteristics and head MRI/A findings between positive and negative patients. All positive patients showed no particular abnormalities in the nasal findings such as olfactory bulb atrophy or thickening of the olfactory mucosa. CONCLUSION: Intracranial lesions in mild patients do not show a clear difference from those in negative patients. This indicates that findings seen in common MRI/A sequences of severe patients are not likely in mild patients, supporting that there is relatively no damage to the central nervous system in mild patients.

Dried blood spots are a valid alternative to venipuncture for COVID-19 antibody testing.

BACKGROUND: Serologic analysis is an important tool towards assessing the humoral response to COVID-19 infection and vaccination. Numerous serologic tests and platforms are currently available to support this line of testing. Two broad antibody testing categories are point-of-care lateral flow immunoassays and semi-quantitative immunoassays performed in clinical laboratories, which typically require blood collected from a finger-stick and a standard venipuncture blood draw, respectively. This study evaluated the use of dried blood spot (DBS) collections as a sample source for COVID-19 antibody testing using an automated clinical laboratory test system. METHODS: Two hundred and ninety-four participants in the BLAST COVID-19 seroprevalence study (NCT04349202) were recruited at the time of a scheduled blood draw to have an additional sample taken via finger stick as a DBS collection. Using the EUROIMMUN assay to assess SARS-CoV-2 anti-spike IgG status, DBS specimens were tested on 7, 14, 21, and 28 days post- collection and compared to the reference serum sample obtained from a blood draw for the BLAST COVID-19 study. RESULTS: SARS-CoV-2 anti-spike IgG status from DBS collections demonstrated high concordance with serum across all time points (7-28 days). However, the semi-quantitative value from DBS collections was lower on average than that from serum, resulting in increased uncertainty around the equivocal-to-positive analytical decision point. CONCLUSIONS: DBS collections can be substituted for venipuncture when assaying for COVID-19 IgG antibody, with samples being stable for at least 28 days at room temperature. Finger-stick sampling can therefore be advantageous for testing large populations for SARS-CoV-2 antibodies without the need for phlebotomists or immediate processing of samples. We have high confidence in serostaus determination from DBS collections, although the reduced semi-quantitative value may cause some low-level positives to fall into the equivocal or even negative range.

Faradaic Impedimetric Immunosensor for Label-Free Point-of-Care Detection of COVID-19 Antibodies Using Gold-Interdigitated Electrode Array.

Label-free electrochemical biosensors have many desirable characteristics in terms of miniaturization, scalability, digitization, and other attributes associated with point-of-care (POC) applications. In the era of COVID-19 and pandemic preparedness, further development of such biosensors will be immensely beneficial for rapid testing and disease management. Label-free electrochemical biosensors often employ [Fe(CN)6]-3/4 redox probes to detect low-concentration target analytes as they dramatically enhance sensitivity. However, such Faradaic-based sensors are reported to experience baseline signal drift, which compromises the performance of these devices. Here, we describe the use of a mecaptohexanoic (MHA) self-assembled monolayer (SAM) modified Au-interdigitated electrode arrays (IDA) to investigate the origin of the baseline signal drift, developed a protocol to resolve the issue, and presented insights into the underlying mechanism on the working of label-free electrochemical biosensors. Using this protocol, we demonstrate the application of MHA SAM-modified Au-IDA for POC analysis of human serum samples. We describe the use of a label-free electrochemical biosensor based on covalently conjugated SARS-CoV-2 spike protein for POC detection of COVID-19 antibodies. The test requires a short incubation time (10 min), and has a sensitivity of 35.4/decade (35.4%/10 ng mL-1) and LOD of 21 ng/mL. Negligible cross reactivity to seasonal human coronavirus or other endogenous antibodies was observed. Our studies also show that Faradaic biosensors are ~17 times more sensitive than non-Faradaic biosensors. We believe the work presented here contributes to the fundamental understanding of the underlying mechanisms of baseline signal drift and will be applicable to future development of electrochemical biosensors for POC applications.

Seroprevalence of SARS-CoV-2 antibodies during the third wave of COVID-19 in the Seoul metropolitan area of Korea.

OBJECTIVES: After the third wave of coronavirus disease 2019 (COVID-19), by mid-February 2021, approximately 0.16% of the Korean population was confirmed positive, which appeared to be among the lowest rates worldwide at that time. However, asymptomatic transmission is challenging for COVID-19 surveillance. Therefore, a community-based serosurvey of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was conducted to understand the effectiveness of Korea's strong containment strategy. METHODS: We collected 5,002 residual sera samples from January 30 to March 3, 2021, from 265 medical facilities in Seoul, 346 in Gyeonggi Province, and 57 in Incheon. Sixty samples from tertiary institutions were excluded. We defined the sub-regions according to the addresses of the medical facilities where the specimens were collected. Elecsys Anti-SARS-CoV-2 was used for screening, and positivity was confirmed using the SARS-CoV-2 sVNT Kit. Prevalence was estimated using sampling weights and the Wilson score interval for a binomial proportion with a 95% confidence interval. RESULTS: Among the 4,942 specimens, 32 and 25 tested positive for COVID-19 in the screening and confirmatory tests, respectively. The overall crude prevalence of SARS-CoV-2 antibodies was 0.51%. The population-adjusted overall prevalence was 0.55% in women and 0.38% in men. The region-specific estimation was 0.67% and 0.30% in Gyeonggi Province and Seoul, respectively. No positive cases were detected in Incheon. CONCLUSIONS: The proportion of undetected cases in Korea remained low as of early 2021. Therefore, an infection control strategy with exhaustive tracing and widespread pre-emptive testing appears to be effective in containing community spread of COVID-19.

COVID-19 Seroprevalence in ED Health Care Professionals Study: A Cross-Sectional Study.

INTRODUCTION: ED health care professionals are at the frontline of evaluation and management of patients with acute, and often undifferentiated, illness. During the initial phase of the SARS-CoV-2 outbreak, there were concerns that ED health care professionals may have been at increased risk of exposure to SARS-CoV-2 due to difficulty in early identification of patients. This study assessed the seroprevalence of SARS-CoV-2 antibodies among ED health care professionals without confirmed history of COVID-19 infection at a quaternary academic medical center. METHODS: This study used a cross-sectional design. An ED health care professional was deemed eligible if they had worked at least 4 shifts in the adult emergency department from April 1, 2020, through May 31, 2020, were asymptomatic on the day of blood draw, and were not known to have had prior documented COVID-19 infection. The study period was December 17, 2020, to January 27, 2021. Eligible participants completed a questionnaire and had a blood sample drawn. Samples were run on the Roche Cobas Elecsys Anti-SARS-CoV-2 antibody assay. RESULTS: Of 103 health care professionals (16 attending physicians, 4 emergency residents, 16 advanced practice professionals, and 67 full-time emergency nurses), only 3 (2.9%; exact 95% CI, 0.6%-8.3%) were seropositive for SARS-CoV-2 antibodies. DISCUSSION: At this quaternary academic medical center, among those who volunteered to take an antibody test, there was a low seroprevalence of SARS-CoV-2 antibodies among ED clinicians who were asymptomatic at the time of blood draw and not known to have had prior COVID-19 infection.

Blunted Post-COVID-19 Humoral Immunity in Patients With CNS Demyelinating Disorders on Anti-CD20 Treatments.

With unclear characteristics of post-infection and post-vaccination immunity, the multiple sclerosis community lacks evidence to guide patients on their continued coronavirus disease 2019 (COVID-19) infection risk. As disease modifying treatments all modulate the immune system, we expect their use to alter acquired immunity to COVID-19, but the specific impact of individual treatments is unclear. To address this, we analyzed the patient and COVID-19 specific characteristics associated with post-infection humoral immunity in 58 patients with central nervous system (CNS) demyelinating disorders in the Boston metropolitan area. Univariate analysis of variance was performed using Mann Whitney U test for continuous variables, and Chi Square or Fisher Exact test for nominal variables. Univariate and stepwise multivariate nominal logistic regression identified clinical characteristics associated with COVID-19 specific nucleocapsid IgG antibody formation post-infection. Our cohort demonstrated a 42% post-infection seropositive rate with a significantly higher rate observed with shorter duration between infection and antibody collection and use of natalizumab over no/other treatment. Use of anti-CD20 treatments compared to no/other treatment was associated with a significantly lower rate of seropositivity. However, only shorter duration between infection and antibody collection as well as use of no/other treatment compared to anti-CD20 treatment were found to be independently associated with increased likelihood of post-infection seropositivity. Additionally, we demonstrate durability of antibody response up to 9 months in a small subset of patients. Thus, our data supports that patients with CNS demyelinating disorders regardless of DMT are able to form a measurable antibody response after COVID-19 infection, and that patients on anti-CD20 treatments form less robust immunity after COVID-19 infection.

Human inhalable antibody fragments neutralizing SARS-CoV-2 variants for COVID-19 therapy.

As of December 2021, coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a global emergency, and novel therapeutics are urgently needed. Here we describe human single-chain variable fragment (scFv) antibodies (76clAbs) that block an epitope of the SARS-CoV-2 spike protein essential for ACE2-mediated entry into cells. 76clAbs neutralize the Delta variant and other variants being monitored (VBMs) and inhibit spike-mediated pulmonary cell-cell fusion, a critical feature of COVID-19 pathology. In two independent animal models, intranasal administration counteracted the infection. Because of their high efficiency, remarkable stability, resilience to nebulization, and low cost of production, 76clAbs may become a relevant tool for rapid, self-administrable early intervention in SARS-CoV-2-infected subjects independently of their immune status.

Seroprevalence of SARS-CoV-2 and assessment of epidemiologic determinants in Portuguese municipal workers.

OBJECTIVES: To assess the seroprevalence of SARS-CoV-2 antibodies in municipal employees of Northern Portugal during the first pandemic wave (May-June 2020) and its association with potentially related risk factors for infection. MATERIAL AND METHODS: The authors assessed municipal employees of 2 cities in Northern Portugal, in whom serological tests to SARS-CoV-2 and an epidemiological survey were applied. The authors assessed the proportion of individuals presenting IgM and/or IgG antibodies to SARS-CoV-2, and evaluated the association between having positive serological test results, epidemiologic variables and clinical presentations. Reported symptoms were evaluated on their sensitivity, specificity, and predictive values. RESULTS: The authors assessed 1696 employees, of whom 22.0% were firefighters, 10.4% were police officers, 10.3% were maintenance workers, and 8.1% were administrative assistants. The seroprevalence of SARS-CoV-2 infection was 2.9% (95% CI: 2.1-3.7%). Administrative assistants comprised the professional group with highest seroprevalence of SARS-CoV-2 (OR = 1.9 in the comparison with other occupational groups, 95% CI: 0.8-4.3, p = 0.126). The seroprevalence of SARS-CoV-2 infection among those who were in direct contact with COVID-19 patients in their professional activity was 3.9%, compared to 2.7% among those who were not in direct contact with such patients (OR = 1.5, 95% CI: 0.8-2.8, p = 0.222). The highest risk of infection was associated with the presence of a confirmed SARS-CoV-2 infection in the household (OR = 17.4, 95% CI: 8.3-36.8, p < 0.001). Living with a healthcare professional was not associated with a higher risk of infection (OR = 1.0, 95% CI: 0.4-2.5, p = 0.934). Anosmia/ dysgeusia was the symptom with the highest positive predictive value (52.2%, 95% CI: 31.8-72.6, p < 0.001) and specificity (99.3%, 95% CI: 98.9-99.7, p < 0.001), while cough was the most prevalent symptom among SARS-CoV-2 seropositive participants (36%). CONCLUSIONS: The authors observed a SARS-CoV-2 seroprevalence of 2.9% among assessed municipal employees. Anosmia/dysgeusia was the COVID-19 symptom which displayed the highest positive predictive value and specificity. Int J Occup Med Environ Health. 2022;35(3):297-307.

Prevalence of maternal obesity at delivery and association with maternal and neonatal outcomes.

INTRODUCTION: Maternal obesity has been linked to adverse outcomes for mothers and their offspring, including, but not limited to gestational hypertension (gHTN), gestational diabetes (GDM), pre-eclampsia, fetal macrosomia, and emergency cesarean section. Recent investigations have also shown that obesity, as defined by a body mass index (BMI) ≥ 30, especially severe obesity (BMI ≥ 40), is a risk factor for both hospitalization and death from COVID-19. OBJECTIVES: The objective of this study is to determine the prevalence and association of maternal obesity at delivery with adverse antenatal, intrapartum, and neonatal outcomes in a cohort of consecutive delivering patients at a tertiary care center in Iowa from May to September 2020. A secondary objective is to determine if maternal obesity has any relationship to past or current COVID-19 infection status at the time of delivery. This is a secondary analysis of a prospective cohort study to analyze obstetric outcomes among COVID-19 infected and uninfected patients. METHODS: We conducted a prospective cohort study using demographic and clinical data obtained from the electronic medical record. Excess plasma was collected from routine blood samples obtained at delivery admission to determine the seroprevalence of COVID-19 antibody using the DiaSorin and Roche antibody assays. Frequency variables were each calculated separately, and a comparison of maternal and neonatal outcomes was conducted using the generalized linear mixed modeling (GLMM) framework to account for varying distributions (normal and binary). RESULTS: 1001 women delivered during the study period and 89.7% met criteria for being overweight or obese; 17.9% met criteria for severe obesity. Women with obesity had 49.8% lower odds of possessing private insurance, and women with severe obesity were less than half as likely to plan to breastfeed at the time of discharge. Women with obesity of any kind had a significantly increased odds of GDM and gHTN, and an increased risk of an infant with macrosomia, hypoglycemia, and NICU admission. No significant association was found between BMI and COVID-19 infection or disease severity. CONCLUSION: This study provides insight into obstetric complications facing women with obesity, especially those with severe obesity. This report serves to highlight potential challenges, such as insurance status and labor complications, that impact women of high BMI to a greater degree when compared to their normal-weight counterparts.

Validation of the COVID-19 IgG/IgM Rapid Test Cassette (BNCP ­ 402 and BNCP402) in a South African setting

Background: Different diagnostic tools could improve early detection of coronavirus disease 2019 (COVID-19). A number of antibody-based serological point-of-care tests have been developed to supplement real-time reverse transcriptase polymerase chain reaction (RT-PCR)-based diagnosis. This study describes the validity of an antibody test, namely the immunoglobulin G (IgG)/immunoglobulin M (IgM) Rapid Test Cassette® (BNCP ­ 402 and BNCP402), manufactured by Spring Healthcare Services. Methods: A prospective cohort validation study was undertaken at Chris Hani Baragwanath Academic Hospital between 16 July 2020 and 12 August 2020. A total of 101 patients admitte as COVID-19 cases under investigation were included in the study. They were divided into two categories depending on time since symptom onset: testing performed within seven days (early cohort) and after seven days (late cohort). The rapid antibody test was compared to the RT-PCR. Results: Overall, the test has a sensitivity and specificity of 85.2% and 80.0%, respectively, for a combination of IgG and IgM. Sensitivity and specificity of IgG testing alone were 81.5% and 85%. Sensitivity improved for testing with increasing time from symptom onset; however, specifity was not significantly different. Conclusion: The study data adds to the body of evidence that because of relatively low sensitivity and specificity, there is a limited role for antibody-based point-of-care testing in the acute phase of COVID-19 infection, as was the case with this IgG/IgM Rapid Test Cassette (BNCP ­ 402 and BNCP402). There may exist a role for such testing in patients recovered from prior COVID-19 infection or in seroprevalence studies; however, additional evaluations at later timepoints from symptom onset are required.

Updated Clinical Evaluation of the CLUNGENE® Rapid COVID-19 Antibody Test.

BACKGROUND: COVID-19 antibody testing has been shown to be predictive of prior COVID-19 infection and an effective testing tool. The CLUNGENE® SARS-COV-2 VIRUS (COVID-19) IgG/IgM Rapid Test Cassette was evaluated for its utility to aide healthcare professionals. METHOD: Two studies were performed by using the CLUNGENE® Rapid Test. (1) An expanded Point-of-Care (POC) study at two clinical sites was conducted to evaluate 99 clinical subjects: 62 positive subjects and 37 negative subjects were compared to RT-PCR, PPA, and NPA (95% CI). Sensitivity was calculated from blood-collection time following symptom onset. (2) A cross-reactivity study was performed to determine the potential for false-positive results from other common infections. RESULTS: The specificity of subjects with confirmed negative COVID-19 by RT-PCR was 100% (95% CI, 88.4-100.0%). The sensitivity of subjects with confirmed positive COVID-19 by RT-PCR was 96.77% (95% CI, 88.98-99.11%). In the cross-reactivity study, there were no false-positive results due to past infections or vaccinations unrelated to the SARS-CoV-2 virus. CONCLUSION: There is a need for a rapid, user-friendly, and inexpensive on-site monitoring system for diagnosis. The CLUNGENE® Rapid Test is a useful diagnostic test that provides results within 15 min, without high-complexity laboratory instrumentation.

Results of Serosurveillance and Forecasting the Third Wave of COVID-19 in an Industrial District in India.

Prevalence of immunoglobulin G (IgG) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in the industrial district of East Singhbhum (Jharkhand, India) from July, August, November, and December 2020 and January 2021 after the first wave and in July 2021 after the second wave of coronavirus disease 2021 (COVID-19) infections may be utilized to find the possibility of a third wave of COVID-19 infections. Based on the trend of the loss of protective IgG antibodies after the first wave and the seropositivity of 75% in the district in July 2021, simple forecasting and proportional estimates of the seropositivity in the next eight months and the estimated maximum number of the cases was done. We also considered the seropositivity without vaccination in July 2021 (63%). Additionally, the trend of the weekly RT-PCR and rapid antigen testing for SARS-CoV-2 may also preemptively predict an imminent wave. Based on the East Singhbhum population and the vaccination coverage with at least one dose till July 2021 (Covishield or Covaxin), it is estimated that a 4-5% monthly vaccination coverage rate of new individuals will not allow the seropositivity to fall below 50% and hold at bay a major wave. Vaccination coverage of 3% or less would allow a continuous drop in acquired immunity in the district and can potentially cause a rise in cases, making the community susceptible to a future surge of infections. A 3-5% vaccination rate of new individuals is unlikely to see a drop in the community seropositivity below 50% and the number of new cases of COVID-19 infections going above 478 to 712 per month at least till March 2022. The assumptions are based on presuming that there will be no new mutant of SARS-CoV-2 that escapes the immunity provided by previous infection or vaccination over the next eight months. However, currently, there is no evidence to speculate on any new variant of concern causing a major wave globally. The B.1.617.2 (delta) variant was first identified in October 2020 and there was a lag of six months to the second surge of COVID-19 infections in East Singhbhum, primarily caused by this variant. Additionally, 3% and above, with a rising weekly trend of reverse transcription-polymerase chain reaction (RT-PCR) positivity for SARS-CoV-2 can provide at least four to eight weeks advance warning before the peak of the wave if an imminent future wave is impending.

Early Serological Response to BNT162b2 mRNA Vaccine in Healthcare Workers.

PURPOSE: Clinical significance and durability of serological response after mRNA COVID-19 vaccines is under investigation. Data on early virological response are limited. To iden-tify potential predictors of antibody durability, circulating antibody levels were longitudinally ex-plored in healthcare workers included in a follow-up program for SARS-CoV-2 infection. Meth-ods: Subjects meeting the inclusion criteria signed an informed consent. Serum samples were col-lected at baseline, before the first BNT162b2 vaccine, at days 7, 21, 31, 90, and 180 days after the first dose. Serological evaluation was performed by QuantiVac Euroimmune anti-S1 antibody as-say. Only subjects followed-up until day 90 are here considered. RESULTS: Of 340 taken into consid-eration, 265 subjects were naive, and 75 COVID-19 experienced. The former showed a progres-sive increase in their antibody levels before day 90 decline, while the latter showed antibody levels reaching a plateau at day 7 and slightly declining at day 90. All showed antibody levels higher than the assay cut-off at day 31 and 90. Among naive, 108 had an early response whose predic-tors were younger age and female gender (OR 0.94, 95% CI 0.91-0.96, p < 0.0001; and OR 2.58, 95% CI 1.48-4.51, p = 0.0009). Naive subjects experienced a day 30/90 decline in antibody levels, whereas experienced did not. Early response was an independent predictor of higher day 30/90 antibody levels decline (OR = 2.05, 95% CI 1.04-4.02; p = 0.037). CONCLUSIONS: Our results suggest that in healthcare workers early response might be inversely associated with antibody levels 90 days after BNT162b2 vaccine.

Pregnancy Outcome, Antibodies, and Placental Pathology in SARS-CoV-2 Infection during Early Pregnancy.

There are reports that pregnant women infected with SARS-CoV-2 not only have increased morbidity but also increased complications and evidence of maternal and fetal vascular malperfusion on placental pathology. This was a retrospective study of pregnant women diagnosed with SARS-CoV-2 infection after March 2020. The results of reverse transcription polymerase chain reaction testing and IgM and IgG antibody testing of the amniotic fluid, cord blood, placenta, and maternal blood were confirmed at delivery. Placentas were evaluated histopathologically. The study included seven pregnant women diagnosed with SARS-CoV-2 infection during pregnancy at a mean gestational age of 14.5 weeks. Out of the seven women, five were infected during the first trimester. The mean gestational age at delivery was 38.4 weeks. The reverse transcription polymerase chain reaction results for maternal plasma, cord blood, placenta, and amniotic fluid were negative and IgG antibodies were detected in maternal plasma and cord blood. On placental pathology, maternal vascular malperfusion was found in only one case, fetal vascular malperfusion in four cases, and inflammatory changes were found in two cases. Pregnancy outcomes for women diagnosed with SARS-CoV-2 infection during early pregnancy are positive and it is likely that maternal antibodies are passed to the fetus, which results in a period of immunity.

Thrombosis of the Portal Vein and Superior Mesenteric Vein in a Patient With Subclinical COVID-19 Infection.

More than 122 million cases of COVID-19 infection have been documented, and hundreds of thousands are being added every day. Several co-morbidities are associated with COVID-19, among which hypercoagulability has garnered the attention of many doctors and researchers. Most cases of vascular thrombosis are noted in intensive care unit (ICU) patients with serious disease; among these, many cases of deep venous thrombosis and pulmonary embolism have been noted. A few cases of portal vein thrombosis have also been documented in ICU patients with severe COVID-19. Here, we present a case of a portal vein and superior mesenteric vein thrombosis in a patient with subclinical COVID-19 infection. Through this case report, we intend to increase the research horizon and wish to help diagnose co-morbidities associated with COVID-19 at an earlier stage.

Mental distress in a clinical nurse due to a false-positive COVID-19 antibody test result during the COVID-19 epidemic in Japan: A case report.

This study suggests the importance of instituting accompanying measures to prevent potential negative mental and social impacts on people receiving false-positive results.

Development and Validation of a Multiplex Microsphere Immunoassay Using Dried Blood Spots for SARS-CoV-2 Seroprevalence: Application in First Responders in Colorado, USA.

Serological testing of large representative populations for antibodies to SARS-CoV-2 is needed to estimate seroprevalence, transmission dynamics, and the duration of antibody responses from natural infection and vaccination. In this study, a high-throughput SARS-CoV-2 multiplex microsphere immunoassay (MMIA) was developed for the receptor binding domain (RBD) and nucleocapsid (N) that was more sensitive than enzyme-linked immunosorbent assay (ELISA) (98% versus 87%). The MMIA was then applied and validated in 264 first responders in Colorado using serum and dried blood spot (DBS) eluates, compared to ELISA, and evaluated for neutralizing antibodies. Four percent (11/264) of first responders were seropositive in July to August 2020. Serum and DBS were highly correlated for anti-RBD and anti-N antibodies (R = 0.83, P < 0.0001 and R = 0.87, P < 0.0001, respectively) by MMIA. The MMIA accurately predicted SARS-CoV-2 neutralizing antibodies using DBS (R = 0.76, P = 0.037). On repeat antibody testing 3 months later, anti-RBD IgG decreased less rapidly than anti-N IgG measured by MMIA, with a median change in geometric median fluorescence intensity of 62% versus 79% (P < 0.01) for anti-RBD and anti-N IgG, respectively. This novel MMIA using DBS could be scalable for rapid and affordable SARS-CoV-2 serosurveillance in the United States and globally.