High seroprevalence of anti-SARS-CoV-2 antibodies in the capital of Chad

Background. Since the start of the COVID-19 pandemic, Chad has had 7,417 confirmed cases and 193 deaths, one of the lowest in Africa. Objective. This study assessed SARS-CoV-2 immunity in N'Djamena. Methods. In August-October 2021, eleven N'Djamena hospitals collected outpatient data and samples. IgG antibodies against SARSCoV- 2 nucleocapsid protein were identified using ELISA. "Bambino Gesu" Laboratory, Rome, Italy, performed external quality control with chemiluminescence assay. Results. 25-34-year-old (35.2%) made up the largest age group at 31.9 12.6 years. 56.4% were women, 1.3 women/men. The 7th district had 22.5% and the 1st 22.3%. Housewives and students dominated. Overall seroprevalence was 69.5% (95% CI: 67.7-71.3), females 68.2% (65.8-70.5) and males 71.2% (68.6-73.8). >44-year-old had 73.9% seroprevalence. Under-15s were 57.4% positive. Housewives (70.9%), civil servants (71.5%), and health workers (9.7%) had the highest antibody positivity. N'Djamena's 9th district had 73.1% optimism and the 3rd district had 52.5%. Seroprevalences were highest at Good Samaritan Hospital (75.4%) and National General Referral Hospital (74.7%). Conclusion. Our findings indicate a high circulation of SARS-CoV- 2 in N'Djamena, despite low mortality and morbidity after the first two COVID-19 pandemic waves. This high seroprevalence must be considered in Chad's vaccine policy.

Antibody levels of COVID-19 vaccine: A comparison between healthy subjects and psychiatric patients on antidepressants

This study compares the serological antibody level post-COVID-19 vaccine among healthy subjects and psychiatric patients on antidepressant therapy. It also examines the difference in antidepressants' side effects experienced by psychiatric patients following the completion of two vaccine doses. A comparative posttest quasi-experimental study was conducted among healthy subjects and psychiatric patients on antidepressant medication in a teaching hospital in Malaysia. Elecsys Anti-SARS-CoV-2 assay was used to detect the antibody titre between weeks 4 and 12 post vaccination. The antidepressant side-effect checklist (ASEC) was used to monitor the occurrence of antidepressant-related side effects pre-and post-vaccination. 24 psychiatric patients and 26 healthy subjects were included. There was no significant difference in the antibody level between the patients (median = 1509 u/ml) and the healthy subjects (median = 995 u/ml). There was no significant worsening in the antidepressant-related side effects. The antibody level post-COVID-19 vaccine did not differ significantly between patients on antidepressant therapy and healthy subjects. Additionally, there was no change in the antidepressant side effects experienced by the patients following the completion of the vaccine.Copyright © 2022, Research Trends (P) LTD.. All rights reserved.

Risk of exposure to Covid-19 in nursing assistants, nurses, and physicians in a university hospital in the face of pandemic.

Objective: Healthcare professionals were the workers most affected by Covid-19, espe-cially during the first waves of the pandemic. Thus, the aim of this study is to evaluate the perceived risk of exposure to Covid-19, the information received and the work participation between nurses, physicians and nursing assistants. Method(s): A cross-sectional study was conducted using an epidemiological survey among nurses, physicians and nursing assistants in a university hospital. Aspect and content validation, cognitive pretest, and piloting of the epidemiological survey was carried out with thirty subjects. A descriptive analysis was per-formed using mean and standard deviation (SD) for quantitative variables and absolute (n) and relative (%) frequencies for qualitative variables. The chi-square test and the ANOVA test were applied to assess the association of the responses with the variables: sex, type of worker, area of work and activity in Covid-19 Units. Result(s): Nurses, physicians and nursing assistants worked mainly in assistance areas and high risk of exposure units. Nursing assistants and nurses had a higher perception of risk. Nurses were less involved in the organiza-tion, but felt more supported by their colleagues. However, physicians felt more supported by their superiors and better care when they had a health problem. Conclusion(s): Nursing assistants and nurses presented higher risk perception, nurses were less involved in the organization of health care, while physicians felt more supported by their superiors.Copyright © 2023, Fundacion Index. All rights reserved.

Knowledge, intention, and practice of wearing face mask by common people to ensure protection against COVID-19 during pandemic

Background: Since the outbreak of global pandemic, wearing face mask not only protects the individual but also limits the spread of corona virus infection in the community. However, certain sociocultural and personal factors have created hinderance in wearing face mask by general people against COVID-19 virus. Aims and Objectives: The aim and objective of this study is to assess the knowledge, intension, and practice of wearing face mask among common people. Material(s) and Method(s): It was a cross-sectional study conducted among general people in a part of Western Odisha after ethical approval. A total of1050 adults above 18 years participated in this study. The data were collected from different locality of the town using a pretested self-administered questionnaire by all authors and research assistants of this project. The period of study was from July 2021 to December 2021. The results were tabulated, processed, and analyzed using SPSS-20. Result(s): Regarding knowledge score, we observed that 57% had average, 18% had poor, and 25% had good knowledge. Furthermore, we found 42% participants had positive intention and 58% had negative intention. Again we assessed that 35% of participants were practicing face mask appropriately and 65% practicing inappropriately. Conclusion(s): In this study, the score of knowledge, intention, and also the practice of wearing face mask against COVID-19 was lower than the average as compared to previous researches. Hence, health authorities should promote the people to wear mask and encourage awareness programs for the benefit of the society.Copyright © 2023, Mr Bhawani Singh. All rights reserved.

Clinical and epidemiologic features of SARS-CoV-2 in dogs and cats compiled through national surveillance in the United States

OBJECTIVE: To characterize clinical and epidemiologic features of SARS-CoV-2 in companion animals detected through both passive and active surveillance in the US. ANIMALS: 204 companion animals (109 cats, 95 dogs) across 33 states with confirmed SARS-CoV-2 infections between March 2020 and December 2021. PROCEDURES: Public health officials, animal health officials, and academic researchers investigating zoonotic SARS-CoV-2 transmission events reported clinical, laboratory, and epidemiologic information through a standardized One Health surveillance process developed by the CDC and partners. RESULTS: Among dogs and cats identified through passive surveillance, 94% (n = 87) had reported exposure to a person with COVlD-19 before infection. Clinical signs of illness were present in 74% of pets identified through passive surveillance and 27% of pets identified through active surveillance. Duration of illness in pets averaged 15 days in cats and 12 days in dogs. The average time between human and pet onset of illness was 10 days. Viral nucleic acid was first detected at 3 days after exposure in both cats and dogs. Antibodies were detected starting 5 days after exposure, and titers were highest at 9 days in cats and 14 days in dogs. CLINICAL RELEVANCE: Results of the present study supported that cats and dogs primarily become infected with SARS-CoV-2 following expo- sure to a person with COVID-19, most often their owners. Case investigation and surveillance that include both people and animals are necessary to understand transmission dynamics and viral evolution of zoonotic diseases like SARS-CoV-2.

Serological Profile of SARS-CoV-2 in Unvaccinated Blood Donors: A Nationwide Study During the Fifth Wave of the Pandemic in Iran

Background: Serological studies can demonstrate pathogen circulation in regional populations and reflect public health mea-sures' effectiveness during different pandemic phases. By late November 2021, coinciding with the third pandemic wave, the sero-prevalence of SARS-CoV-2 spike IgG antibodies among the Iranian population was 32.63%. Objective(s): This study aimed to assess the Iranian population's seroprevalence during the fifth pandemic wave by analyzing donated blood samples. Method(s): This population-based cross-sectional study was conducted on Iranian blood donors referred to all 31 main provincial capitals between August 2021 and September 2021. The participants selected through quota sampling were asked to complete a questionnaire on socio-demographics and coronavirus disease 2019 (COVID-19)-related information. Also, SARS-CoV-2 spike IgG antibodies were measured in serum samples using SARS-CoV-2 enzyme-linked immunosorbent assay (ELISA) kits. The seroprevalence was weighted based on the gender and age groups of the population and then adjusted for test performance. Result(s): Totally 3,339 blood donors participated in this study. The overall population-weighted seroprevalence adjusted for test performance was 52.67% (95% confidence interval (CI): 50.14-55.21). Seroprevalence was higher among participants with a high school diploma (55.45%, 95% CI 50.61-60.29), a positive history of close contact with COVID-19 patients (65.23%, 95% CI 60.83-69.63), and previous positive COVID-19 PCR tests (86.51%, 95% CI 82.32-90.7). Conclusion(s): More than half of the study population was exposed to SARS-CoV-2, indicating a 1.7-fold increase in the seroprevalence between late November 2020 and mid-September 2021. Our finding illuminated the pattern of Iran's fifth wave of the pandemic.Copyright © 2023, Author(s).

A cross-sectional study on the seroprevalence of the SARS-CoV-2 IgG antibody in patients with cancer from central Kerala

Background: Patients with cancer are vulnerable to coronavirus disease 2019 (COVID-19). Given the rising number of COVID-19 cases and relaxation of stringent COVID-19 protocols, assessment of the level of protective immunity to COVID-19 in patients with cancer has assumed importance. Objective(s): Our primary objective was to evaluate the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in patients with cancer. Material(s) and Method(s): We conducted a cross-sectional study on 100 patients with solid tumors attending our Oncology Department at the Believers Church Medical College, Kerala, India, between December 2020 and June 2021. Seroprevalence was assessed using the VITROS Anti-SARS-CoV-2 IgG test (Ortho-Clinical Diagnostics, Rochester, NY, USA). Additionally, we assessed the factors associated with seropositivity and collected data regarding the general experience of patients with cancer during the pandemic. Result(s): The median age of the participants was 62 years (IQR, 53-69.8);52 (52%) were males. The seroprevalence of the SARS-CoV-2 IgG antibodies was 11% (95% CI, 4.8-17.1). Age < 50 years was the only factor that was significantly associated with a higher rate of COVID-19 antibodies (77% vs 8.9% in patients >= 50 years;P = 0.007), and sex, smoking, and the use of alcohol did not show any association. The majority (77/100, 77%) of the patients were worried about contracting COVID-19 infection;some even deferred cancer-directed treatment because of the fear of visiting health care settings. Conclusion(s): Low seroprevalence of SARS-CoV-2 IgG antibodies in unvaccinated patients with cancer is a matter of concern as it indicates that many of these patients are still vulnerable to infection. There is an urgent need to continue implementing strict safety measures in oncology centers and to encourage widespread COVID-19 vaccination to prevent the uncontrolled spread of COVID-19 among patients with cancer. (Funded by the institution, Believers Church Medical College, Kerala).Copyright © 2023 Neurology India, Neurological Society of India Published by Wolters Kluwer - Medknow.

ASSESSMENT OF POST-VACCINATION COLLECTIVE IMMUNITY AGAINST NEW CORONAVIRUS INFECTION (COVID-19) AMONG SERVICEMEN OF THE ARMED FORCES OF THE RUSSIAN FEDERATION

The recent vaccination campaign targeting the new coronavirus infection (COVID-19) carried out in the Armed Forces of the Russian Federation, on the background of the current unstable global pandemic situation, makes it necessary to study post-vaccination population immunity to the SARS-CoV-2 virus and thus identify key features of immunity in organized military collectives. In the future, this will make it possible to objectively assess the risks of a worsening pandemic situation, effectively adjust the ongoing sanitary and anti-epidemic measures aimed at preserving and strengthening the health of military personnel, as one of the main conditions for maintaining the combat readiness of the Armed Forces of the Russian Federation. During a study conducted on epidemic indications, it was found that vaccination with Gam-Covid-Vac contributes to the formation of collective immunity with 95% effectiveness. A gender-based analysis of the immune response showed that the proportion of persons who lack class G immunoglobulins to SARS-CoV-2 among females is twice than that among men (9.3% and 4.7%, respectively). Seroprevalence indicators, classified by blood group, range from 94.4% (AB (IV) Rh–) to 97.4% (A (II) Rh–). There were no significant differences in seroprevalence between groups of people with different blood groups;however, the highest value of seroprevalence was seen among military personnel with blood group A (II) Rh–. In this context, it is advisable to continue monitoring the formation of immunity in individuals with various blood groups. The results obtained made it possible to form a primary medical and social "portrait” of a serviceman with the most adequate immune response to the introduction of the Gam-Covid-Vac vaccine (a man under the age of 20 with blood type A (II) Rh–) and to draw a conclusion about the high effectiveness of vaccination in military units (formations) staffed by conscripts and military educational organizations. The article can be used under the CC BY-NC-ND 4.0 license © Authors, 2022.

Seroprevalence of SARS-CoV- 2 in children of school-going age in district Swabi, Pakistan

Introduction: Earlier estimates of SARS-CoV- 2 do not accurately account for the extent of undiagnosed infections in children, who typically experience mild or asymptomatic disease. The purpose of this study was to estimate the seroprevalence of SARS-CoV- 2 antibodies in children from District Swabi, one of the populous districts of Pakistan, and to identify symptoms most frequently associated with seropositivity. Methodology: We used ELISA to test for the presence of antibodies, IgM and IgG, in blood samples collected from 246 children of school-going age (5-16 years old) selected randomly from the district of Swabi, Pakistan. This study was approved by Khyber Medical University, Peshawar, Ethical Board, and Advanced Studies Review Board. Data were collected on a purposefully built questionnaire. Result(s): Overall, 2.0% of our participants were seropositive for IgM, whereas 23.1% were seropositive for IgG. Older age, female gender, and contact history were significantly associated with higher seropositivity. Symptoms associated with seropositivity were: fever (98.0%), cough (90.0%), sore throat (79.0%), coryza (68.0%), myalgia (61.0%), loss of sense of smell and taste (49.0%), and vomiting or diarrhoea (8.0%). Although 77.6% of our IgG seropositive participants recalled experiencing flu-like symptoms, none of the participants in this study had visited the doctor or were tested for SARS-COV- 2. We found IgG titres to be significantly higher in symptomatic children. Conclusion(s): The number of undiagnosed infections in children may be substantially larger than the official accounts. Sparse data are available regarding coronavirus disease in children, particularly in low middle-income countries (LMIC). The most frequently symptoms were fever, cough, sore throat, coreza, myalgia, loss of sense of smell and taste and lastly vomiting and diarrhoea. Serological studies provide valuable insight into the immunological status of a population, and can prove vital when considering future strategies.

Seroprevalence of anti-SARS-CoV-2 antibodies in high-risk occupational and low-risk groups in southwestern Iran

Background: Monitoring the spread of SARS-CoV-2 has been considered by the World Health Organization (WHO). We examined the prevalence of anti-SARS-CoV-2 immunoglobulin antibodies in southwestern Iran in spring 2020. The circulation of SARS-CoV-2 is high in the general population, especially among health care workers (HCWs) who are in close contact with patients. Objectives: The aim of this study was to determine the prevalence of anti-SARS-CoV-2 antigen in high-risk occupational and low-risk groups to investigate risk factors for serum positivity in Shiraz, southwestern Iran. Methods: A cross-sectional survey was performed on 366 participants (204 from high-risk and 162 from low-risk subjects). IgG and IgM antibodies were detected using Pishtaz Teb COVID-19 ELISA Kits to evaluate SARS-CoV-2-antigen in serum samples. After enzyme-linked immunosorbent assay (ELISA), serum prevalence, as well as IgG/IgM positive factors, was determined using logistic regression. Results: From July to September 2020 (a few months after reporting the first case of COVID-19 cases in Iran), out of 366 survived people, 72 (40.9%) were IgG positive, and 50 (27.5%) were IgM positive. The frequency of positive serology for IgG and IgM antibodies in individuals aged < 30 years was higher in the low-risk group than in the high-risk group. Multivariate logistic regression showed that headache (OR 0.312 [95% CI: 0.136 - 0.717]) and cough (OR 0.427 [95% CI: 0.182 - 1.004]) factors were associated with IgG or IgM positive serology. Conclusions: Between July and September 2020, the prevalence of anti-SARS-CoV-2 antigen was high in Shiraz. The prevalence of SARS-CoV-2 IgG/IgM antibodies in the high-risk group and their family as low risk was shown to increase viral infection due to close contact with COVID 19 patients than in the general population. Several factors were found to be related to the prevalence of anti-SARS-CoV-2 antigen that needs to be considered by policymakers to determine what to do about the SARS-CoV-2 pandemic.

Prevalence of Antibodies to COVID-19 Due to Infection or Vaccination in US Adults.

OBJECTIVE: -Determine the seroprevalence of SARS-CoV-2 infection and vaccination in a population applying for life insurance. SETTING: -This is a cross-sectional study of 2584 US life insurance applicants, to determine the seroprevalence of antibodies to COVID-19. This convenience sample was selected on two consecutive days April 25-26, 2022. RESULTS: -For COVID-19, 97.3% are seropositive, and 63.9% have antibodies to nucleocapsid protein, a marker of prior infection. An additional, 33.7% have been vaccinated with no serologic evidence of infection. METHODOLOGY: -Serum and urine samples from a nationwide group of insurance applicants for routine risk assessment were collected. The examination of applicants typically occurs, in their homes, their place of employment, or a clinic. The paramedic exam occurs 7-14 days after the insurance application. Before the exam, an office assistant calls the applicant and inquires if they have been in contact with a person with SARS-CoV-2, been ill within the last 2 weeks, felt sick, or recently had a fever. If the applicant answers yes, the exam is rescheduled. Before sample collection, the applicant reads and signs a consent form to release medical information and testing. Next, the examiner records the applicant's blood pressure, height, and weight. Then, a blood and a urine sample are collected and sent with the consent form to our laboratory via Federal Express. On April 25-26, 2022, we tested 2584 convenience samples from adult insurance applicants for the presence of antibodies to nucleocapsid and spike proteins from SARS-CoV-2. As a standard practice, we reported the client-specified test profile results to our life insurance carriers. In contrast, the COVID-19 test results were only available to the authors. Patient and Public Involvement.-There was no patient involvement in study design, reporting of results, or journal publication selection. There was patient consent to publish de-identified study results. No public involvement occurred in the creation or completion of the study. The authors thank the participants in this study for approving the use of their blood samples to further society's understanding of the SARS-CoV-19 pandemic. Ethics Review.-Western Institutional Review Board reviewed the study design and determined it to be exempt under the Common Rule and applicable guidance. Therefore, it is exempt under 45 CFR § 46.104(d)(4) from using de-identified study samples for epidemiologic investigation, WIRB Work Order #1-1324846-1. In addition, all test subjects had signed a consent allowing research of their blood and urine samples with the removal of personally identifiable information. RESULTS: -The combined seroprevalence for antibodies to nucleocapsid, a marker of prior infection, and antibodies to spike protein, an indicator of either previous infection or vaccination, was 97.3%. Higher infection rates occur in younger vs older age groups, with a non-statistical difference for vaccinated and acquired natural immunity. For the age group 16-84, the total estimated seroprevalence of COVID-19 in the US is 249 million cases. CONCLUSIONS: -The US population has widespread immune resistance to current variants of COVID-19 due to prior infection or vaccination. The infectivity of new variants and silent disease, independent of previous infection or vaccination, are the driving force behind the sporadic increase in clinical SARS-CoV-2 cases.

Changes in SARS-CoV-2 seroprevalence and population immunity in Finland, 2020-2022.

Studying the prevalence of SARS-CoV-2 specific antibodies (seroprevalence) allows for assessing the impact of epidemic containment measures and vaccinations and estimating the number of infections regardless of viral testing. We assessed antibody-mediated immunity to SARS-CoV-2 induced by infections and vaccinations from April 2020 to December 2022 in Finland by measuring serum IgG to SARS-CoV-2 nucleoprotein (N-IgG) and spike glycoprotein from randomly selected 18-85-year-old subjects (n = 9794). N-IgG seroprevalence remained at <7% until the last quartile (Q) of 2021. After the emergence of the Omicron variant, N-IgG seroprevalence increased rapidly and was 31% in Q1/2022 and 54% in Q4/2022. Seroprevalence was highest in the youngest age groups from Q2/2022 onwards. We did not observe regional differences in seroprevalence in 2022. We estimated that 51% of the Finnish 18-85-year-old population had antibody-mediated hybrid immunity induced by a combination of vaccinations and infections by the end of 2022. In conclusion, major shifts in the COVID-19 pandemic and resulting population immunity could be observed by serological testing.

Seroprevalence of SARS-CoV-2 in Brazil: A systematic review and meta-analysis.

OBJECTIVES: To summarize the data on SARS-CoV-2 seroprevalence surveys conducted in Brazil before the introduction of vaccines METHODS: The authors conducted a systematic review and meta-analysis on the seroprevalence of SARS-CoV-2 infection in Brazil. The present review followed the PRISMA guidelines. The authors searched Medline, Embase, and LILACS databases for serologic surveys conducted in the Brazilian population, in the period from 01/10/2019 to 07/11/2021, without language restrictions. The authors included studies that presented data concerning SARS-CoV-2 antibodies seroprevalence in Brazil and had a sample size ≥50 individuals. Considering the expected heterogeneity between studies, all analyses were performed using the random effects model, and heterogeneity was assessed using the I2 statistic RESULTS: Of 586 publications identified in the initial searches, 54 were included in the review and meta-analysis, which contained the results of 135 surveys, with 336,620 participants. The estimated seroprevalence was 11.0%, ranging from 1.0% to 83.0%, with a substantial heterogeneity (I2 = 99.55%). In subgroup analyses, the authors observed that the prevalence of SARS-CoV-2 antibodies was 13.0% in blood donors, 9.0% in the population-based surveys, 13% in schoolchildren, and 11.0% in healthcare workers. CONCLUSIONS: Seroprevalence increases over time. Large differences were observed among the regions of the country. It was higher in the Northern region, decreasing towards the South. The present results may contribute to the analysis of the spread of SARS-CoV-2 infection in the Brazilian population before vaccination, one of the factors that may be influencing the clinical presentation of COVID-19 cases related to the new variants, as well as the effectiveness of the vaccination program.

Prevalence of SARS-CoV-2 antibodies among Belgian nursing home residents and staff during the primary COVID-19 vaccination campaign.

BACKGROUND: Nursing home residents (NHR) and staff have been disproportionally affected by the COVID-19 pandemic and were therefore prioritised in the COVID-19 vaccination strategy. However, frail older adults, like NHR, are known to have decreased antibody responses upon vaccination targeting other viral antigens. OBJECTIVES: As real-world data on vaccine responsiveness, we assessed the prevalence of SARS-CoV-2 antibodies among Belgian NHR and staff during the primary COVID-19 vaccination campaign. METHODS: In total, we tested 1629 NHR and 1356 staff across 69 Belgian NHs for the presence of SARS-CoV-2 IgM/IgG antibodies using rapid tests. We collected socio-demographic and COVID-19-related medical data through questionnaires. Sampling occurred between 1 February and 24 March 2021, in a randomly sampled population that received none, one or two BNT162b2 vaccine doses. RESULTS: We found that during the primary vaccination campaign with 59% of the study population fully vaccinated, 74% had SARS-CoV-2 antibodies. Among fully vaccinated individuals only, fewer residents tested positive for SARS-CoV-2 antibodies (77%) than staff (98%), suggesting an impaired vaccine-induced antibody response in the elderly, with lowest seroprevalences observed among infection naïve residents. COVID-19 vaccination status and previous SARS-CoV-2 infection were predictors for SARS-CoV-2 seropositivity. Alternatively, age ≥ 80 years old, the presence of comorbidities and high care dependency predicted SARS-CoV-2 seronegativity in NHR. CONCLUSION: These findings highlight the need for further monitoring of SARS-CoV-2 immunity upon vaccination in the elderly population, as their impaired humoral responses could imply insufficient protection against COVID-19. TRIAL REGISTRATION: This study was retrospectively registered on ClinicalTrials.gov (NCT04738695).

One-Year Follow-Up of Seroprevalence of SARS-CoV-2 Infection and Anxiety among Health Workers of a French Cancer Center: The PRO-SERO-COV Study.

Infection of SARS-CoV-2 among health workers (HWs) in contact with cancer patients has been a major issue since the beginning of the pandemic. We aimed to assess the serological immune status of SARS-CoV-2 infection among these HWs. A prospective cohort study was initiated in the comprehensive cancer center of the Nouvelle-Aquitaine region (NA, France). Volunteer HWs working on March 2020 without active infection or symptoms of COVID-19 completed a self-questionnaire and had a blood test at inclusion, at 3 and 12 months. Positive serological status of SARS-CoV-2 infection was defined by anti-nucleocapsid antibodies and/or IgG anti-spike antibodies, except at 12 months due to vaccine. Half of the HWs were included (N = 517) and 89% were followed for three months (N = 500) and one year (N = 462). Seroprevalence of SARS-CoV-2 infection was 3.5% (95% CI: 1.9-5.1), 6.2% (95% CI: 4.1-8.3), and 10% (95% CI: 7.2-12.7) on June-September 2020, September 2020-January 2021, and June-October 2021, respectively. At 12 months, 93.3% had detectable antibodies with 80% vaccinated in the first three months of vaccine availability. The COVID-19-free policy of the institution, respect for barrier gestures, high and early vaccination of HWs, and low prevalence of SARS-CoV-2 in NA may explain the low rate of seropositivity among the HWs of the Institut Bergonié.

Factors Associated with Reported COVID-like Symptoms and Seroprevalence Data Matched with COVID-like Symptoms in Slums and Non-Slums of Two Major Cities in Bangladesh.

OBJECTIVES: To examine the levels and socio-demographic differentials of: (a) reported COVID-like symptoms; and (b) seroprevalence data matched with COVID-like symptoms. METHODS: Survey data of reported COVID-like symptoms and seroprevalence were assessed by Roche Elecsys® Anti-SARS-CoV-2 immunoassay. Survey data of 10,050 individuals for COVID-like symptoms and seroprevalence data of 3205 individuals matched with COVID-like symptoms were analyzed using bivariate and multivariate logistic analysis. RESULTS: The odds of COVID-like symptoms were significantly higher for Chattogram city, for non-slum, people having longer years of schooling, working class, income-affected households, while for households with higher income had lower odd. The odds of matched seroprevalence and COVID-like symptoms were higher for non-slum, people having longer years of schooling, and for working class. Out of the seropositive cases, 37.77% were symptomatic-seropositive, and 62.23% were asymptomatic, while out of seronegative cases, 68.96% had no COVID-like symptoms. CONCLUSIONS: Collecting community-based seroprevalence data is important to assess the extent of exposure and to initiate mitigation and awareness programs to reduce COVID-19 burden.

Seroprevalence of SARS-CoV-2 and Vaccination Coverage among Residents of a Lower-Middle-Class Population in the Federal District, Brazil.

Estimating seroprevalence and vaccination coverage against COVID-19 is crucial to the development of well-targeted public health policies at the local level. Here, we estimated seroprevalence and vaccination coverage in a lower-middle-class population in Brazil. We conducted an observational, cross-sectional, population-based survey from 24 September to 19 December 2021. CMIA tests were used to detect anti-SARS-CoV-2 IgG against the N-protein. The overall seroprevalence was 24.15% (177/733), and vaccination coverage was 91.40% (670/733); 72.09% (483/670) were fully vaccinated. Among vaccinated participants, seroprevalence was 24.77% (95% CI 21.50-28.04; 166/670), with a prevalence ratio (PR) of 1.03 (95% CI 0.98-1.08; p-value 0.131). Among participants who received an mRNA vaccine with S-based epitope (485), seroprevalence was 16.29% (95% CI 13.04-19.85; 79/485). Among unvaccinated participants, seroprevalence was 17.46% (95% CI 10.04-28.62; 11/63). Finally, in spite of the political climate and other possible causes for vaccine hesitancy, the positive Brazilian culture towards vaccination might have curbed hesitancy.

Using a multiplex serological assay to estimate time since SARS-CoV-2 infection and past clinical presentation in malagasy patients.

Background: The world is facing a 2019 coronavirus (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this context, efficient serological assays are needed to accurately describe the humoral responses against the virus. These tools could potentially provide temporal and clinical characteristics and are thus paramount in developing-countries lacking sufficient ongoing COVID-19 epidemic descriptions. Methods: We developed and validated a Luminex xMAP® multiplex serological assay targeting specific IgM and IgG antibodies against the SARS-CoV-2 Spike subunit 1 (S1), Spike subunit 2 (S2), Spike Receptor Binding Domain (RBD) and the Nucleocapsid protein (N). Blood samples collected periodically for 12 months from 43 patients diagnosed with COVID-19 in Madagascar were tested for these antibodies. A random forest algorithm was used to build a predictive model of time since infection and symptom presentation. Findings: The performance of the multiplex serological assay was evaluated for the detection of SARS-CoV-2 anti-IgG and anti-IgM antibodies. Both sensitivity and specificity were equal to 100% (89.85-100) for S1, RBD and N (S2 had a lower specificity = 95%) for IgG at day 14 after enrolment. This multiplex assay compared with two commercialized ELISA kits, showed a higher sensitivity. Principal Component Analysis was performed on serologic data to group patients according to time of sample collection and clinical presentations. The random forest algorithm built by this approach predicted symptom presentation and time since infection with an accuracy of 87.1% (95% CI = 70.17-96.37, p-value = 0.0016), and 80% (95% CI = 61.43-92.29, p-value = 0.0001) respectively. Interpretation: This study demonstrates that the statistical model predicts time since infection and previous symptom presentation using IgM and IgG response to SARS-CoV2. This tool may be useful for global surveillance, discriminating recent- and past- SARS-CoV-2 infection, and assessing disease severity. Fundings: This study was funded by the French Ministry for Europe and Foreign Affairs through the REPAIR COVID-19-Africa project coordinated by the Pasteur International Network association. WANTAI reagents were provided by WHO AFRO as part of a Sero-epidemiological "Unity" Study Grant/Award Number: 2020/1,019,828-0 P·O 202546047 and Initiative 5% grant n°AP-5PC-2018-03-RO.