Seroepidemiological study on coinfection of toxoplasmosis and active tuberculosis in Northern Iran: a case control study.

Coinfection of tuberculosis (TB) and human parasitic infections is common in developing countries. There is little information about the prevalence of Toxoplasma gondii (T. gondii) infection among TB patients in Iran. In this case-control study, anti-toxoplasma antibodies were measured by ELISA method in 100 patients with active tuberculosis and 100 healthy individuals who were matched in terms of sex, age, and place of residence. Anti-T. gondii IgG antibodies were diagnosed in 62% of TB patients (95% CI 53-71%) and 70% of control subjects (95% CI 62-78%). Anti-T. gondii IgM antibodies were found in 1% of both TB patients and control group. The seroprevalence of T. gondii infection was not significantly different between TB patients and healthy individuals (P > 0.05). None of the assessed sociodemographic and behavioral factors was recognized as a risk factor for toxoplasmosis in TB infected patients. Moreover, the level of anti-T. gondii IgG antibodies concentration in TB patients was significantly higher than in control subjects and revealed skewness towards humoral immune response in TB patients. Coinfection of toxoplasmosis and tuberculosis was prevalent but T. gondii infection was independent of active TB in this co-endemic area.

Estimates of protection levels against SARS-CoV-2 infection and severe COVID-19 in Germany before the 2022/2023 winter season: the IMMUNEBRIDGE project.

PURPOSE: Despite the need to generate valid and reliable estimates of protection levels against SARS-CoV-2 infection and severe course of COVID-19 for the German population in summer 2022, there was a lack of systematically collected population-based data allowing for the assessment of the protection level in real time. METHODS: In the IMMUNEBRIDGE project, we harmonised data and biosamples for nine population-/hospital-based studies (total number of participants n = 33,637) to provide estimates for protection levels against SARS-CoV-2 infection and severe COVID-19 between June and November 2022. Based on evidence synthesis, we formed a combined endpoint of protection levels based on the number of self-reported infections/vaccinations in combination with nucleocapsid/spike antibody responses ("confirmed exposures"). Four confirmed exposures represented the highest protection level, and no exposure represented the lowest. RESULTS: Most participants were seropositive against the spike antigen; 37% of the participants ≥ 79 years had less than four confirmed exposures (highest level of protection) and 5% less than three. In the subgroup of participants with comorbidities, 46-56% had less than four confirmed exposures. We found major heterogeneity across federal states, with 4-28% of participants having less than three confirmed exposures. CONCLUSION: Using serological analyses, literature synthesis and infection dynamics during the survey period, we observed moderate to high levels of protection against severe COVID-19, whereas the protection against SARS-CoV-2 infection was low across all age groups. We found relevant protection gaps in the oldest age group and amongst individuals with comorbidities, indicating a need for additional protective measures in these groups.

Hepatitis A hospitalisations in the United States and risk factors for inpatient mortality: A nationwide population study, 1998-2020.

Hepatitis A virus infections in the United States have been declining; however, recent widespread outbreaks have brought the disease back into the spotlight. We aim to describe the epidemiology of hepatitis A hospitalisations from 1998 to 2020 in the United States and investigate risk factors for inpatient mortality. We utilised the National Inpatient Sample database and identified hepatitis A-related hospitalisations using ICD-9 and ICD-10 diagnosis codes. Demographic and clinical data including death, coinfections, comorbidities and pregnancy status were extracted. Data were analysed by logistic and Poisson regression. We identified a total of 213,681 hepatitis A-related hospitalisations between 1998 and 2020, with hospitalisation rates ranging between 22.4 per 1,000,000 and 62.9 per 1,000,000. Between 1998 and 2015, the hospitalisation rate for hepatitis A was decreasing (IRR = 0.98; 95% CI: 0.97-0.98; p < .001); however, between 2015 and 2020, it increased overall (IRR = 1.22; 95% CI: 1.21-1.23; p < .001). The overall inpatient mortality rate was 2.7%. Age ≥55 years (OR = 1.84; 95% CI: 1.41-2.40; p < .001), alcoholic cirrhosis (OR = 2.53; 95% CI: 1.64-3.90; p < .001), ascites (OR = 2.65; 95% CI: 1.86-3.78; p < .001), hepatorenal syndrome (OR = 9.04; 95% CI: 5.93-13.80; p < .001), heart failure (OR = 1.76; 95% CI: 1.29-2.39; p < .001), pulmonary hypertension (OR = 2.02; 95% CI: 1.28-3.19; p = .003) and malignant neoplasm (OR = 1.75; 95% CI: 1.25-2.45; p = .001) were associated with increased odds of mortality. Tobacco use disorder (OR = 0.52; 95% CI: 0.38-0.70; p < .001) was associated with decreased odds of mortality. None of the hepatitis A-associated hospitalisations involving pregnant women resulted in death. Hepatitis A hospitalisations initially declined but increased rapidly after 2015. Certain risk factors can be used to predict prognosis of hospitalised patients.

Bridging the gap - estimation of 2022/2023 SARS-CoV-2 healthcare burden in Germany based on multidimensional data from a rapid epidemic panel.

OBJECTIVES: Throughout the SARS-CoV-2 pandemic, Germany like other countries lacked adaptive population-based panels to monitor the spread of epidemic diseases. METHODS: To fill a gap in population-based estimates needed for winter 2022/23 we resampled in the German SARS-CoV-2 cohort study MuSPAD in mid-2022, including characterization of systemic cellular and humoral immune responses by interferon-γ-release assay (IGRA) and CLIA/IVN assay. We were able to confirm categorization of our study population into four groups with differing protection levels against severe COVID-19 courses based on literature synthesis. Using these estimates, we assessed potential healthcare burden for winter 2022/23 in different scenarios with varying assumptions on transmissibility, pathogenicity, new variants, and vaccine booster campaigns in ordinary differential equation models. RESULTS: We included 9921 participants from eight German regions. While 85% of individuals were located in one of the two highest protection categories, hospitalization estimates from scenario modeling were highly dependent on viral variant characteristics ranging from 30-300% compared to the 02/2021 peak. Our results were openly communicated and published to an epidemic panel network and a newly established modeling network. CONCLUSIONS: We demonstrate feasibility of a rapid epidemic panel to provide complex immune protection levels for inclusion in dynamic disease burden modeling scenarios.

Nonnegligible Seroprevalence and Predictors of Murine Typhus, Japan.

To elucidate the epidemiology of murine typhus, which is infrequently reported in Japan, we conducted a cross-sectional study involving 2,382 residents of rickettsiosis-endemic areas in Honshu Island during August-November 2020. Rickettsia typhi seroprevalence rate was higher than that of Orientia tsutsugamushi, indicating that murine typhus is a neglected disease.

Population-based sero-epidemiological investigation of SARS-CoV-2 infection in Somalia.

OBJECTIVES: To explore the burden of coronavirus disease 2019 (COVID-19) in Somalia by measuring the seroprevalence of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the general population. METHODS: We recruited a convenience sample of 2751 participants from among individuals attending outpatient and inpatient departments of public health facilities, or their accompanying family members. Participants were interviewed to collect sociodemographic data and provided a blood sample. We calculated seropositivity rates overall and by sex, age group, state, residence, education and marital status. We used logistic regression analysis - odds ratios and 95% confidence intervals (CI) - to investigate sociodemographic correlates of seropositivity. RESULTS: The overall seropositivity rate was 56.4% (95% CI 54.5-58.3%), while 8.8% of participants reported being previously diagnosed with COVID-19 by July 2021. In the regression analysis, after controlling for covariates, urban residence was significantly asscoiated with seropositivity: OR = 1.74 (95% CI: 1.19-2.55). CONCLUSIONS: Our results show a high seroprevalence rate of SARS-CoV-2 in the Somali population (56.4%), and indicate that many infections have not been captured by the country's surveillance system resulting in considerable under-reporting.

Tularemia seroprevalence in humans in the region of the Hittite-Arzawa War (Inner Aegean Region), where the first biological weapon was used 3300 years ago.

BACKGROUND: : According to Egyptian records, tularemia emerged in the Canaan region, where it was first identified and spread to Anatolia over the Euphrates. It was used as an active biological weapon for the first time in the Hittite-Arzawa War in 1320-1318 BC. This study aimed to investigate the seroprevalence of tularemia in the Inner Aegean Region, which is thought to be the region where this war was fought 3300 years ago. METHODS: Tularemia seropositivity in humans was investigated in 27 villages/neighborhoods in 3 districts in each of Manisa, Kütahya, and Usak provinces. Before the study, the participants were informed about the disease via posters, and their blood samples were taken following filling out the questionnaire. Microagglutination tests were performed using in-house tularemia antigen and V plate for serological experiments. Rose-Bengal test was also performed on seropositive sera. RESULTS: Of the total of 410 people, 226 (55.12%) were male. The mean age of the volunteers was 43.72 years. The highest participation was from Kütahya Province. According to the results of the tularemia microagglutination test, seropositivity was detected in 6 cases. It was determined that all of the seropositive volunteers were in Kütahya. When the tularemia antibody titers were examined, seropositivity was determined at 1/20-1/160 titers. No positivity was detected in the Rose-Bengal test for cross-reaction. DISCUSSION: Kütahya has been identified as a risky region in terms of tularemia in the Inner Aegean Region. In order to use the resources in the country economically, first of all, the risk areas in terms of tularemia should be determined by serological studies in all regions. In order to increase awareness about the disease, physicians and filiation teams should be trained in risky areas. Surveillance studies should be conducted to identify and monitor possible sources in areas identified as risky.

Non-patient-related SARS-CoV-2 exposure from colleagues and household members poses the highest infection risk for hospital employees in a German university hospital: follow-up of the prospective Co-HCW seroprevalence study.

PURPOSE: The Co-HCW study is a prospective, longitudinal, single-center observational study that aims to assess the SARS-CoV-2 seroprevalence and infection status in staff members of Jena University Hospital (JUH) in Jena, Germany. METHODS: This follow-up study covers the observation period from 19th May 2020 to 22nd June 2021. At each of the three voluntary study visits, participants filled out a questionnaire regarding their SARS-CoV-2 exposure and provided serum samples to detect specific SARS-CoV-2 antibodies. Participants who were tested positive for antibodies against nucleocapsid and/or spike protein without previous vaccination and/or reported a positive SARS-CoV-2 PCR test were regarded to have been infected with SARS-CoV-2. Multivariable logistic regression modeling was applied to identify potential risk factors for infected compared to non-infected participants. RESULTS: Out of 660 participants that were included during the first study visit, 406 participants (61.5%) were eligible for the final analysis as their COVID-19 risk area (high-risk n = 76; intermediate-risk n = 198; low-risk n = 132) did not change during the study. Forty-four participants [10.8%, 95% confidence interval (95%CI) 8.0-14.3%] had evidence of a current or past SARS-CoV-2 infection detected by serology (n = 40) and/or PCR (n = 28). No association between SARS-CoV-2 infection and the COVID-19 risk group according to working place was detected. However, exposure to a SARS-CoV-2 positive household member [adjusted OR (AOR) 4.46, 95% CI 2.06-9.65] or colleague (AOR 2.30, 95%CI 1.10-4.79) was found to significantly increase the risk of a SARS-CoV-2 infection. CONCLUSION: Our results demonstrate that non-patient-related SARS-CoV-2 exposure posed the highest infection risk for hospital staff members of JUH.

Seroprevalence of SARS-CoV-2 Antibodies in Denmark: Results of Two Nationwide Population-Based Surveys, February and May 2021.

Background: Seroprevalence studies can be used to measure the progression of national COVID-19 epidemics. The Danish National Seroprevalence Survey of SARS-CoV-2 infections (DSS) was conducted as five separate surveys between May 2020 and May 2021. Here, we present results from the two last surveys conducted in February and May 2021. Methods: Persons aged 12 or older were randomly selected from the Danish Population Register and those having received COVID-19 vaccination subsequently excluded. Invitations to have blood drawn in local test centers were sent by mail. Samples were analyzed for whole Immunoglobulin by ELISA. Seroprevalence was estimated by sex, age and geography. Comparisons to vaccination uptake and RT-PCR test results were made. Results: In February 2021, we found detectable antibodies in 7.2% (95% CI: 6.3-7.9%) of the invited participants (participation rate 25%) and in May 2021 in 8.6% (95% CI: 7.6-9.5%) of the invited (participation rate: 14%). Seroprevalence did not differ by sex, but by age group, generally being higher among the <50 than 50+ year-olds. In May 2021, levels of seroprevalence varied from an estimated 13% (95% CI: 12-15%) in the capital to 5.2% (95% CI: 3.4-7.4%) in rural areas. Combining seroprevalence results with vaccine coverage, estimates of protection against infection in May 2021 varied from 95% among 65+ year-olds down to 10-20% among 12-40 year-olds. In March-May 2021, an estimated 80% of all community SARS-CoV-2 infections were diagnosed by RT-PCR and captured by surveillance. Conclusion: Seroprevalence estimates doubled during the 2020-21 winter wave of SARS-CoV-2 infections and then stabilized as vaccinations were rolled out. The epidemic affected large cities and younger people the most. Denmark saw comparatively low infections rates, but high test coverage; an estimated four out of five infections were detected by RT-PCR in March-May 2021.

Seroprevalence of anti-hepatitis A virus antibody in Iraq.

Background: Hepatitis A virus infection is widespread in Iraq, therefore, assessing its seroprevalence is important for infection control at the community level. Aims: To determine hepatitis A virus seroprevalence in a representative sample in Duhok Governorate, northern Iraq; evaluate changes in the epidemiological pattern; and assess factors associated with its seropositivity. Methods: This cross-sectional study was conducted from July 2020 to November 2021. Random cluster sampling was used to select participants aged 5-74 years. Hepatitis A virus immunoglobulin G (IgG) was determined among the participants and demographic data were collected on sex, residency (urban or rural), age, history of jaundice, number of family members (≤ five or > five), and sources of drinking water. Results: A total of 1052 participants (625 males and 427 females) were enrolled. The overall seroprevalence of hepatitis A virus IgG was 68.3%: 24.4% in ages 5-10 years; 38.3% in ages 11-15; 86.9% in ages 16-20; 85.4% in ages 21-30; 95.3% in ages 31-40; and 89.2% in ages > 40 years. Factors significantly associated with hepatitis A virus IgG positivity were rural residence, male sex and family size greater than five (all P < 0.01). Conclusion: Hepatitis A virus seroprevalence in Iraq has been declining since the past decade, indicating intermediate-to-low endemicity of hepatitis A virus. However, people are still many susceptible, indicating the need for hepatitis A virus vaccination in the country.

Guest edited collection serological study of SARS-CoV-2 antibodies in japanese cats using protein-A/G-based ELISA.

BACKGROUND: Little is known about the epidemic status of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in cats in Japan due to insufficiently reliable seroepidemiological analysis methods that are easy to use in cats. RESULTS: We developed a protein-A/G-based enzyme-linked immunosorbent assay (ELISA) to detect antibodies against SARS-CoV-2 in cats. The assay was standardized using positive rabbit antibodies against SARS-CoV-2. The ELISA results were consistent with those of a conventional anti-feline-immunoglobulin-G (IgG)-based ELISA. To test the protein-A/G-based ELISA, we collected blood samples from 1,969 cats that had been taken to veterinary clinics in Japan from June to July 2020 and determined the presence of anti-SARS-CoV-2 antibodies. Nine cats were found to have SARS-CoV-2 S1-specific IgG, of which 4 had recombinant receptor-binding domain-specific IgG. Of those 9 samples, one showed neutralizing activity. Based on these findings, we estimated that the prevalence of SARS-CoV-2 neutralizing antibodies in cats in Japan was 0.05% (1/1,969 samples). This prevalence was consistent with the prevalence of neutralizing antibodies against SARS-CoV-2 in humans in Japan according to research conducted at that time. CONCLUSIONS: Protein-A/G-based ELISA has the potential to be a standardized method for measuring anti-SARS-CoV-2 antibodies in cats. The infection status of SARS-CoV-2 in cats in Japan might be linked to that in humans.

Regional seropositivity for Borrelia burgdorferi and associated risk factors: findings from the Rhineland Study, Germany.

BACKGROUND: Lyme borreliosis is the most prevalent vector-borne disease in Europe, and numbers might increase due to climate change. However, borreliosis is not notifiable in North Rhine-Westphalia (NRW), Germany. Hence, little is known about the current human seroprevalence in NRW. However, the proportion of Borrelia burgdorferi sensu lato-infected ticks has increased in a NRW nature reserve. The literature suggests increasing age and male sex as risk factors for seropositivity, whereas the influence of socioeconomic status is controversial. Thus, we aimed to determine regional seropositivity for Borrelia burgdorferi sensu lato (B. burgdorferi s.l.) and its risk factors in the Rhineland Study population in Bonn, NRW, and to compare it with previous surveys to evaluate potential effects of climate change. METHODS: We assessed seropositivity in 2865 Rhineland Study participants by determining immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies for B. burgdorferi s.l. using a two-step algorithm combining enzyme-linked immunosorbent assay tests and line immunoblots. We calculated the odds of being classified as IgG or IgM positive as a function of age, sex, and educational level using binomial logistic regression models. We applied varying seropositivity classifications and weights considering age, sex and education to compensate for differences between the sample and regional population characteristics. RESULTS: IgG antibodies for B. burgdorferi s.l. were present in 2.4% and IgM antibodies in 0.6% of the participants (weighted: 2.2% [IgG], 0.6% [IgM]). The likelihood of IgG seropositivity increased by 3.0% (95% confidence interval [CI] 1.5-5.2%) per 1 year increase in age. Men had 1.65 times the odds for IgG seropositivity as women (95% CI 1.01-2.73), and highly educated participants had 1.83 times the odds (95% CI 1.10-3.14) as participants with an intermediate level of education. We found no statistically significant link between age, sex, or education and IgM seropositivity. Our weighted and age-standardized IgG seroprevalence was comparable to the preceding serosurvey German Health Interview and Examination Survey for Adults (DEGS) for NRW. CONCLUSIONS: We confirmed that increasing age and male sex are associated with increased odds for IgG seropositivity and provide evidence for increased seropositivity in the highly educated group. B. burgdorferi s.l. seropositivity remained constant over the past decade in this regional German population.

Prevalence of SARS-CoV-2 infection and SARS-CoV-2-specific antibody detection among healthcare workers and hospital staff of a university hospital in Colombia.

Objective: The aim of this study was to determine current and previous SARS-COV-2 infection, and describe risk factors associated with seropositivity, among HCWs and hospital staff between June and October of 2020. Methodology: Data from the day of enrollment for a prospective cohort study were analyzed to determine point prevalence and seroprevalence of SARS-CoV-2 infection in HCWs and hospital staff of a university hospital in Colombia. Respiratory samples were collected to perform RT-PCR tests, along with blood samples to measure SARS-CoV-2 IgM and IgG antibodies. Data on nosocomial and community risk factors for infection were also collected and analyzed. Findings: 420 HCWs and hospital staff members were included. The seroprevalence at baseline was 23.2%, of which 10.7% had only IgM antibodies, 0.7% had IgG, and 11.7% had IgM and IgG. The prevalence of acute SARS-CoV-2 infection was 1.9%. Being a nurse assistant was significantly associated with seropositivity when compared with all other job duties (PR 2.39, 95% CI 1.27-3.65, p = 0.01). Conclusions: Overall SARS-CoV-2 prevalence was 1.9% and seroprevalence was 23.15%. Nurse assistants, medical doctors or students, and laboratory workers had a higher possibility of being SARS-CoV-2 seropositive.

Seroprevalence against Diphtheria in Pregnant Women and Newborns in Colombia: New Arguments to Promote Maternal Immunization.

The tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine is recommended during pregnancy for neonatal protection against pertussis, although little is known of the protection it provides against diphtheria. The work used a cross-sectional design to estimate seroprevalence against diphtheria in 805 pregnant women with ≥37 gestation weeks and their newborns whose deliveries were attended in eight hospitals randomly chosen from a subregion of Antioquia, Colombia and to explore factors related with maternal protection. Levels of IgG antibodies were determined by using a commercial enzyme-linked immunosorbent assay test. Placental transfer of antibodies and crude and adjusted prevalence ratio (aPR) were analyzed to describe factors related with maternal protection against diphtheria. Protection against diphtheria was observed in 91.7% (95% CI 90.3-93.0) of the pregnant women and 93.1% (95% CI 91.7-94.4) of newborns, whose antibody levels were positively correlated (Spearman's r = 0.769; p = 0.000). Maternal protection could be influenced by having been vaccinated during the current pregnancy (aPR 0.85, 95% CI: 0.82-0.93). The protective effect of vaccination during pregnancy and the efficiency of maternal antibody transfers were detected. Public health efforts should focus on increasing Tdap vaccination during each pregnancy to protect mothers and newborns against diphtheria.

Successful seroconversion against diphtheria and tetanus induced through maternal vaccination in a region of Colombia.

PURPOSE: This study aims to compare protection against diphtheria and tetanus conferred on the mother and the neonate before and after maternal vaccination against tetanus, diphtheria, and acellular pertussis (Tdap), transfer of antibodies, and the variables that could impact on the protection. MATERIALS AND METHODS: The study followed a cohort of 200 pregnant women from a region in Colombia, contacted during prenatal control before vaccination and upon delivery. The work determined immunoglobulin G antibodies against diphtheria and tetanus of pregnant women and umbilical cord. The proportion of protection, the geometric mean of the concentration, and the transfer of maternal antibodies were calculated. The protection profile of the pregnant women was explored by using multiple correspondence analysis. RESULTS: The concentration of antibodies against diphtheria was significant before and after vaccination of the pregnant women (p=0.000) with proportions of 85.0% and 97.5%, respectively, and of 98.6% in the umbilical cord, with significant antibody correlation (Spearman's coefficient=0.668, p=0.01). Sero-protection against tetanus before vaccination was at 71.0%, after at 92.6%, and in the umbilical cord at 95.9%, with significant antibody concentration before and after vaccination (p=0.000) and antibody correlation (Spearman's coefficient=0.936, p=0.01). Sero-protection was higher when the pregnant women were vaccine 8 to 11 weeks before delivery. Unprotected pregnant women were those not vaccinated during pregnancy. CONCLUSION: The high proportion of protection against diphtheria and tetanus and the placental transfer support the need to promote maternal immunization with Tdap.

The seroprevalence of the hepatitis B virus in Italian medical students after 3 decades since the introduction of universal vaccination.

OBJECTIVES: Since 1991 hepatitis B vaccination has been mandatory for all newborns in Italy. The aim of the study was to verify the long-term seroprevalence and the efficacy of hepatitis B vaccination in medical students of the University of Siena. MATERIAL AND METHODS: A cross-sectional observational study was conducted on a population of 850 medical students of the University of Siena (322 males and 528 females, mean age: 23 years) by obtaining from the medical reports the serological analysis data for the total anti-hepatitis B antibodies (HBsAb) and information on hepatitis B vaccination (number of vaccine doses, age at the first vaccination, time since the final vaccination dose, country of origin). Raw odds ratios (ORs) and 95% confidence intervals (CIs) were initially calculated to evaluate the association between 2 variables. The adjusted ORs were then calculated using a multivariate logistic regression model to study the association between the variables and the possible confounding factors. RESULTS: Overall, 593 students (69.76%) were immunized against hepatitis B, while 257 (30.24%) had HBsAb antibody titer <10 mIU/ml. From the OR calculation, an inverse correlation emerged between seropositivity to hepatitis B and age, and between seropositivity to hepatitis B and the age at the first vaccination dose. There was also a correlation between seropositivity and the number of vaccination doses received. By performing the multivariate logistic analysis, correlations with these variables were confirmed. CONCLUSIONS: A significant part of the studied population was not immunized against hepatitis B virus, despite the fact that vaccination had been carried out as prescribed by law. The results of the study reaffirm the importance of health surveillance in subjects at biological risk such as medical students. Int J Occup Med Environ Health. 2022;35(1):75-80.

Respuesta inmunitaria al SARS-CoV-2 y factores asociados previo a la vacunación, en personal de salud de atención primaria en una comuna de Santiago, Chile

Resumen Introducción: La pandemia de COVID-19 surgida en China a fines de 2019, se extendió rápidamente por el mundo, con casi 600 millones de casos y 6,3 millones de fallecidos en la actualidad. Los más afectados fueron los trabajadores de la salud con al menos tres veces más riesgo que la comunidad general de contraer la enfermedad. La mayoría de los estudios sobre seroprevalencia en trabajadores de la salud, se enfocan en establecimientos de atención hospitalaria y no se ha indagado con igual intensidad sobre lo que ocurre en la Atención Primaria de Salud (APS). Objetivos: Determinar prevalencia de SARS-CoV-2 mediante anticuerpos IgG en personal de atención primaria de comuna de La Pintana y explorar sus características clínicas y factores de riesgo, previo a la vacunación en Chile. Metodología: Diseño transversal realizado en noviembre 2020. Se recogieron datos sociodemográficos y clínicos mediante entrevista cara a cara, previa firma de consentimiento. Se determinó IgG específica mediante ELISA que utiliza proteína N y S. Las diferencias entre sujetos positivos y negativos se estudiaron mediante análisis bivariado y para asociaciones encontradas, se desarrollaron modelos multivariados controlando potenciales variables de confusión. El estudio contó con la aprobación del Comité Ético Científico de la Universidad del Desarrollo. Resultados: Participaron 463 funcionarios (51,4%) encontrando prevalencia de 21,8%. Los factores de riesgo fueron edad menor, ser médico y haber sido contacto estrecho de un caso. El 22% fue asintomático. Entre quienes presentan anosmia o ageusia, la probabilidad de IgG+ fue superior a 70%. Los títulos de anticuerpos aumentan significativamente con la gravedad. Conclusiones: La prevalencia en personal de atención primaria encontrada es concordante con la evidencia previa en trabajadores de salud. La menor edad y la profesión de médico se asocian a un mayor riesgo de enfermar.

Abstract Background: The COVID-19 pandemic that emerged in Wuhan, China at the end of 2019, spread rapidly around the world with almost 600 million cases and 6.3 million deaths today. The most affected were health workers with at least three times the risk of contracting the disease than the general community. Most studies on seroprevalence in health workers focus on hospital care establishments and what happens in Primary Health Care (PHC) has not been investigated with the same intensity. Aim: To determine the prevalence of SARS-CoV-2 using IgG antibodies in primary health care personnel in La Pintana commune, risk factors and clinical characteristics, prior to vaccination in Chile. Methods: A cross-sectional design carried out in November 2020. Sociodemographic and clinical data were collected through face-to-face interviews, after providing informed consent. Specific IgG was determined by ELISA using N and S proteins. The differences between positive and negative subjects were studied using bivariate analysis and multivariate models, controlling for potential confounding variables. The study was approved by the Universidad del Desarrollo Scientific Ethics Committee. Results: 463 employees (51.4%) participated, finding a prevalence of 21.8%. The risk factors found were younger age, being a physician and having been in close contact with a case. 22% were asymptomatic. Among those with anosmia/ageusia, the probability of IgG+ was greater than 70%. Antibody titers increase with severity. Conclusions: Prevalence found in primary health care personnel is consistent with previous evidence. Younger age and medical profession are associated with a higher risk of illness.

SARS-CoV-2 seroprevalence in Mongolia: Results from a national population survey.

BACKGROUND: With the global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in early 2020, Mongolia implemented rapid emergency measures and did not report local transmission until November 2020. We conducted a national seroprevalence survey to monitor the burden of SARS-CoV-2 in Mongolia in the months surrounding the first local transmission. METHODS: During October-December 2020, participants were randomly selected using age stratification and invited for interviews and blood samples at local primary health centres. We screened for total SARS-CoV-2 antibodies, followed by two-step quantitative SARS-CoV-2 IgG serology tests for positive samples. Weighted and test-adjusted seroprevalences were estimated. We used chi-square, Fisher's exact and other tests to identify variables associated with seropositivity. FINDINGS: A total of 5000 subjects were enrolled. We detected SARS-CoV-2 IgG antibodies in 72 samples. Crude seroprevalence of SARS-CoV-2 antibodies was 1·44% (95%CI,1·21-1·67). Population weighted and test-adjusted seroprevalences were 1·36% (95%CI,1·11-1·63) and 1·45% (95%CI,1·11-1·63), respectively. Age, sex, geographical, and occupational factors were not associated with seropositivity (p>0·05). Symptoms and signs within past 3 months and seropositivity were not associated at the time of the survey (p>0·05). INTERPRETATION: SARS-CoV-2 seroprevalence in Mongolia was low in the first year of the pandemic potentially due to strong public health measures, including border restrictions, educational facilities closure, earlier adoption of mask-wearing and others. Our findings suggest large-scale community transmission could not have occurred up to November 2020 in Mongolia. Additional serosurveys are needed to monitor the local pandemic dynamic and estimate how far from herd immunity Mongolia will be following-up with vaccination programme in 2021 and 2022. FUNDING: World Health Organisation, WHO UNITY Studies initiative, with funding by the COVID-19 Solidarity Response Fund and the German Federal Ministry of Health (BMG) COVID-19 Research and development. TRANSLATION: Cyrillic and Traditional Mongolian translation of abstract is available on appendix section.

Seroepidemiological survey on chikungunya in endemic zones for arboviruses in Brazil, 2019.

This study aimed to identify the seroprevalence of chikungunya and its associated factors in the city of Quixadá, Ceará, Brazil. We also aimed to identify the spatial distribution patterns of positive cases. A cross-sectional survey was conducted with a questionnaire about clinical symptoms, socioeconomic and demographic factors, and a 10 ml blood sample was collected and analysed by ELISA. For the bivariate analysis, we use the chi-square test, a prevalence ratio and its 95% confidence interval. A robust Poisson hierarchical regression was used to adjust for confounders. The Kernel density was performed for the spatial analysis. A total of 409 samples were analysed; of them, 70.7% were seropositive for previous exposure to chikungunya virus (CHIKV). High seropositivity for CHIKV was higher in female participants (75.5%; PR = 1.23; 95% CI: 1.06-1.43), those aged 31 years or more (74.3%; PR = 1.62; 95% CI: 1.04-2.52), and those with elementary education level (75.0%; PR = 1.30; 95% CI: 1.06-1.60). There were also high seroprevalence in those with less than a minimum wage per month (89.5%; PR = 1.59; 95% CI: 1.11-2.30), housewives (87.5%; PR = 1.64; 95% CI: 1.24-2.18) and unemployed (80.0%; PR = 1.50; 95% CI: 1.10-2.06). After adjusting for age, morning stiffness was the only chikungunya symptom that remained associated (PR = 1.20; 95% CI: 1.06-1.37; p < .001). There was an area of high density of cases in the downtown and two areas of medium density in nearby regions. Otherwise, the higher seroprevalence rates were in the peripherical neighbourhoods. There is a hyperendemicity of CHIKV in Quixadá, and most cases are spatially contiguous. The main associated clinical sign is morning stiffness, but other factors such as low income and spending a longer time at home were significantly associated with higher seroprevalence.

Prevalence of SARS-CoV-2 antibodies in Denmark: nationwide, population-based seroepidemiological study.

Seroprevalence studies have proven an important tool to monitor the progression of the coronavirus disease 2019 (COVID-19) pandemic. We present results of consecutive population-based seroprevalence surveys performed in Denmark in 2020. In spring, late summer and autumn/winter of 2020, invitation letters including a questionnaire covering symptoms were sent to representative samples of the population above 12 years and to parents of children below 18 years in the sample. Blood samples were analysed for total Ig and seroprevalence estimates per population segment were calculated and compared to other surveillance parameters. Based on 34 081 participants (participation rate 33%), seroprevalence estimates increased from 1.2% (95%CI: 0.3-1.9%) in May to 4.1% (95%CI: 3.1-4.9%) in December 2020. Seroprevalence estimates were roughly three times higher in those aged 12-29 years compared to 65 + and higher in metropolitan municipalities. By December 2020, 1.5% of the population had tested positive by RT-PCR. Infected individuals in older age groups were hospitalised several fold more often than in younger. Amongst seropositives, loss of taste/smell were the more specific symptoms, 32-56% did not report any symptoms. In more than half of seroconverted families, we did not see evidence of transmission between generations. Seroprevalence increased during 2020; adolescents were primarily infected in the autumn/winter. Denmark has a high per capita test rate; roughly one undiagnosed infection of SARS-CoV-2 were estimated to occur for each diagnosed case. Approximately half were asymptomatically infected. The epidemic appears to have progressed relatively modestly during 2020 in Denmark.