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1.
Indian J Med Res ; 155(1): 171-177, 2022 01.
Article in English | MEDLINE | ID: covidwho-2201777

ABSTRACT

Background & objectives: Serology testing is essential for immunological surveillance in the population. This serosurvey was conducted to ascertain the cumulative population immunity against SARS-CoV-2 among adults in Jammu district and to understand the association of seropositivity with sociodemographic and clinical correlates. Methods: On September 30 and October 1, 2020, a household survey was done in 20 villages/wards chosen from 10 health blocks in district Jammu, India. Demographic, clinical and exposure information was collected from 2000 adults. Serum samples were screened for IgG antibodies using COVID Kavach MERILISA kit. Tests of association were used to identify risk factors associated with IgG positivity. Crude odds ratio with 95 per cent confidence intervals (CIs) was calculated during univariate analysis followed by logistic regression. Results: Overall adjusted seroprevalence for SARS-CoV-2 was 8.8 per cent (95% CI: 8.78-8.82); it varied from 4.1 per cent in Chauki choura to 16.7 per cent Pallanwalla across 10 blocks in the district. Seropositivity was observed to be comparatively higher in 41-50 and 61-70 yr age groups, among males and in rural areas. Fever, sore throat, cough, dyspnoea, myalgias, anosmia, ageusia, fatigue, seizures, history of exposure, medical consultation, hospitalization and missing work showed significant association with seropositivity on univariate analysis. On logistic regression, only sore throat, myalgia and missing work showed significant adjusted odds of IgG positivity. Extrapolation to adult population suggested that exposure to SARS-CoV-2 was 14.4 times higher than reported cases, translating into Infection fatality rate of 0.08 per cent. Interpretation & conclusions: Since a major part of population was immunologically naive, all efforts to contain COVID-19 need to be vigorously followed while these baseline results provide an important yardstick to monitor the trends of COVID-19 and guide locally appropriate control strategies in the region.


Subject(s)
COVID-19 , Pharyngitis , Adult , Antibodies, Viral , COVID-19/epidemiology , Humans , Immunoglobulin G , Male , SARS-CoV-2 , Seroepidemiologic Studies
2.
Front Cell Infect Microbiol ; 12: 932563, 2022.
Article in English | MEDLINE | ID: covidwho-2198700

ABSTRACT

In Brazil, the coronavirus disease 2019 (COVID-19) epidemic spread rapidly in a heterogeneous way, mainly due to the different socioeconomic and behavioral characteristics of different regional populations and different evaluation periods. We performed a cross-sectional study including 1,337 individuals (first wave = 736/second wave = 601) after the first two waves of COVID-19 in the city of Belém, the capital of the state of Pará. The detection of IgG anti-SARS-CoV-2 antibodies was performed using an enzyme-linked immunosorbent assay test followed by statistical analysis using the RStudio program. Our results showed an increase in the seroprevalence (first wave= 39.1%/second wave= 50.1%) of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG antibodies in the population of Belém from the first to the second pandemic wave. Advanced age, primary or secondary education level, lack of social isolation, and a low frequency of protective mask use were considered risk factors for SARS-CoV-2 infection during the first wave compared to the second wave. This study is one of the firsts to provide important information about the dynamics of virus circulation and the groups vulnerable to exposure in the two major periods. Our data emphasize the socioeconomic characteristics of the affected population and that nonpharmacological prevention measures are crucial for combating the pandemic.


Subject(s)
COVID-19 , Antibodies, Viral , Brazil/epidemiology , COVID-19/epidemiology , Cross-Sectional Studies , Humans , Immunoglobulin G , Risk Factors , SARS-CoV-2 , Seroepidemiologic Studies
3.
JMIR Public Health Surveill ; 7(9): e30406, 2021 09 01.
Article in English | MEDLINE | ID: covidwho-2141343

ABSTRACT

BACKGROUND: Data on how SARS-CoV-2 enters and spreads in a population are essential for guiding public policies. OBJECTIVE: This study seeks to understand the transmission dynamics of SARS-CoV-2 in small Brazilian towns during the early phase of the epidemic and to identify core groups that can serve as the initial source of infection as well as factors associated with a higher risk of COVID-19. METHODS: Two population-based seroprevalence studies, one household survey, and a case-control study were conducted in two small towns in southeastern Brazil between May and June 2020. In the population-based studies, 400 people were evaluated in each town; there were 40 homes in the household survey, and 95 cases and 393 controls in the case-control study. SARS-CoV-2 serology testing was performed on participants, and a questionnaire was applied. Prevalence, household secondary infection rate, and factors associated with infection were assessed. Odds ratios (ORs) were calculated by logistic regression. Logistics worker was defined as an individual with an occupation focused on the transportation of people or goods and whose job involves traveling outside the town of residence at least once a week. RESULTS: Higher seroprevalence of SARS-CoV-2 was observed in the town with a greater proportion of logistics workers. The secondary household infection rate was 49.1% (55/112), and it was observed that in most households (28/40, 70%) the index case was a logistics worker. The case-control study revealed that being a logistics worker (OR 18.0, 95% CI 8.4-38.7) or living with one (OR 6.9, 95% CI 3.3-14.5) increases the risk of infection. In addition, having close contact with a confirmed case (OR 13.4, 95% CI 6.6-27.3) and living with more than four people (OR 2.7, 95% CI 1.1-7.1) were also risk factors. CONCLUSIONS: Our study shows a strong association between logistics workers and the risk of SARS-CoV-2 infection and highlights the key role of these workers in the viral spread in small towns. These findings indicate the need to focus on this population to determine COVID-19 prevention and control strategies, including vaccination and sentinel genomic surveillance.


Subject(s)
COVID-19/epidemiology , COVID-19/transmission , Communicable Diseases, Imported/epidemiology , Occupations/statistics & numerical data , Transportation/statistics & numerical data , Adolescent , Adult , Brazil/epidemiology , Case-Control Studies , Child , Child, Preschool , Cities/epidemiology , Family Characteristics , Female , Humans , Infant , Infant, Newborn , Male , Middle Aged , Risk Factors , Seroepidemiologic Studies , Young Adult
4.
JMIR Public Health Surveill ; 7(9): e26409, 2021 09 09.
Article in English | MEDLINE | ID: covidwho-2141311

ABSTRACT

BACKGROUND: The development of a successful COVID-19 control strategy requires a thorough understanding of the trends in geographic and demographic distributions of disease burden. In terms of the estimation of the population prevalence, this includes the crucial process of unravelling the number of patients who remain undiagnosed. OBJECTIVE: This study estimates the period prevalence of COVID-19 between March 1, 2020, and November 30, 2020, and the proportion of the infected population that remained undiagnosed in the Canadian provinces of Quebec, Ontario, Alberta, and British Columbia. METHODS: A model-based mathematical framework based on a disease progression and transmission model was developed to estimate the historical prevalence of COVID-19 using provincial-level statistics reporting seroprevalence, diagnoses, and deaths resulting from COVID-19. The framework was applied to three different age cohorts (< 30; 30-69; and ≥70 years) in each of the provinces studied. RESULTS: The estimates of COVID-19 period prevalence between March 1, 2020, and November 30, 2020, were 4.73% (95% CI 4.42%-4.99%) for Quebec, 2.88% (95% CI 2.75%-3.02%) for Ontario, 3.27% (95% CI 2.72%-3.70%) for Alberta, and 2.95% (95% CI 2.77%-3.15%) for British Columbia. Among the cohorts considered in this study, the estimated total number of infections ranged from 2-fold the number of diagnoses (among Quebecers, aged ≥70 years: 26,476/53,549, 49.44%) to 6-fold the number of diagnoses (among British Columbians aged ≥70 years: 3108/18,147, 17.12%). CONCLUSIONS: Our estimates indicate that a high proportion of the population infected between March 1 and November 30, 2020, remained undiagnosed. Knowledge of COVID-19 period prevalence and the undiagnosed population can provide vital evidence that policy makers can consider when planning COVID-19 control interventions and vaccination programs.


Subject(s)
COVID-19/epidemiology , Undiagnosed Diseases/epidemiology , Adult , Aged , Alberta/epidemiology , British Columbia/epidemiology , COVID-19/diagnosis , Cohort Studies , Humans , Middle Aged , Models, Theoretical , Ontario/epidemiology , Prevalence , Quebec/epidemiology , Seroepidemiologic Studies
5.
Rural Remote Health ; 22(3): 6751, 2022 07.
Article in English | MEDLINE | ID: covidwho-2146087

ABSTRACT

INTRODUCTION: Coronavirus disease-19 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a global pandemic, giving rise to a serious global health threat. Many countries including Greece have seen a two-wave pattern of reported cases, with a first wave in spring and a second in autumn of 2020. METHODS: A cross-sectional seroprevalence study was designed to measure the prevalence of IgG antibodies with a quantitative SARS-CoV-2 IgG lab-based serology test, chemiluminescent microparticle immunoassay, against novel coronavirus in rural areas in Greece after the second pandemic wave. The study was conducted on 29 January 2021 in a rural semi-closed area, the municipality of Deskati, prefecture of western Macedonia in Greece after the second pandemic wave. RESULTS: Sixty-nine participants were included in this study. The present study demonstrated a high prevalence of COVID-19 infection (31 of 69 total participants; 45%) and those who were working in the public sector were at higher risk of COVID-19 infection in comparison to their counterparts in private sector (p=0.05364), (relative risk 2.64; 95% confidence interval 1.001-7.086). CONCLUSION: The study presents data showing a high prevalence of herd immunity for COVID-19 in a semi-closed area in Greece. These findings might help to understand the characteristics of this second wave, the behaviour and danger of SARS-CoV-2 in rural areas in Greece and Europe generally.


Subject(s)
COVID-19 , COVID-19/epidemiology , Cross-Sectional Studies , Greece/epidemiology , Humans , Immunoglobulin G , Prevalence , Rural Population , SARS-CoV-2 , Seroepidemiologic Studies , Workplace
6.
Indian J Public Health ; 66(Supplement): S66-S70, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-2144163

ABSTRACT

Background: The age group of 5-17 years belongs to the vulnerable segment of the population for COVID-19 infection in India. Seroprevalence in this population can therefore allow inferences to be made about the extent of infection. Objectives: The objective of this study was to assess the seroprevalence and to determine the factors associated with COVID-19 antibody among children aged 5-17 years in an urban and rural area of Kochi, Kerala. Methods: A community-based cross-sectional study was undertaken in the urban and rural field practice areas of the community medicine department in a medical college, Kochi. A semi-structured questionnaire was used to collect information about sociodemographic data, history related to COVID-19, and the severe acute respiratory syndrome coronavirus 2 antibody test result. Blood samples were collected and tested for the presence of COVID-19 antibodies using the Wantai test kit after attaining informed assent from the parent/guardian. Results: The seroprevalence of the COVID-19 antibody was 48.3% among participants. The seroprevalence of COVID-19 antibody was higher among children of mothers with skilled/unskilled occupation, residents of rural area, above poverty line category, those with a history of COVID-19, and those who had a history of contact with COVID-19-positive patients. Conclusion: Half of the study population were COVID antibody positive, and the rest were at risk of infection. Therefore, adherence to COVID-19 guidelines is essential to control further spread of infection among children.


Subject(s)
COVID-19 , Child , Female , Humans , Child, Preschool , Adolescent , Seroepidemiologic Studies , Cross-Sectional Studies , India/epidemiology , Antibodies, Viral
7.
Front Public Health ; 10: 1021871, 2022.
Article in English | MEDLINE | ID: covidwho-2142354

ABSTRACT

Background: Correctional workers are at increased risk of SARS-CoV-2 infection. We examined the seroprevalence of SARS-CoV-2, determined the effects of carceral and occupational exposures on seropositivity, and explored predictors of COVID-19 vaccine uptake among correctional workers in Quebec, Canada. Methods: We conducted a cross-sectional seroprevalence study in three provincial prisons. The primary and secondary outcomes were SARS-CoV-2 antibody seropositivity (Roche Elecsys® serology test) and self-reported COVID-19 vaccination status ("fully vaccinated" defined as two doses or prior infection plus one dose), respectively. Poisson regression models with robust standard error were used to examine the effect of occupational variables with SARS-CoV-2 seropositivity and predictors of COVID-19 vaccine uptake. Estimates are presented as crude and adjusted prevalence ratios (aPR) with 95% confidence intervals (95% CI). Results: From 14 July to 15 November 2021, 105/600 (18%) correctional workers tested positive across three prisons (range 11-21%); 76% were fully vaccinated. Seropositivity was affected by prison occupation (aPR 1.59, 95% CI 1.11-2.27 for correctional officers vs. all other occupations) and low perceived concern of SARS-CoV-2 acquisition (aPR 1.62, 95% CI 1.11-2.38 for not/hardly worried vs. somewhat/extremely worried). Predictors of being fully vaccinated included race/ethnicity (aPR 0.86, 95% CI 0.76-0.99 for visible minority vs. White), presence of comorbidities (aPR 1.14, 95% CI 1.02-1.28 for > 2 vs. none), and prison occupation (aPR 0.82, 95% CI 0.73-0.92 for correctional officers vs. all other occupations). Conclusions: Correctional officers were most likely to have acquired SARS-CoV-2, but least likely to be vaccinated, underscoring the importance of addressing both occupational risks and COVID-19 vaccine hesitancy to mitigate future outbreaks.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Seroepidemiologic Studies , COVID-19 Vaccines , Cross-Sectional Studies , Quebec/epidemiology , COVID-19/epidemiology , COVID-19/prevention & control , Vaccination , Occupations
8.
Front Immunol ; 13: 1030238, 2022.
Article in English | MEDLINE | ID: covidwho-2142035

ABSTRACT

Objective: To analyze the positivity and levels of SARS-CoV-2 antibodies in vaccinated children to evaluate the humoral immune response of vaccination on pediatric population. Analysis on the causes of antibody positivity in unvaccinated children. Methods: A retrospective study was conducted on children who were admitted to the Children's Hospital Affiliated to Capital Institute of Pediatrics. The clinical data of serological testing of SARS-CoV-2 immunoglobulin M (IgM) and IgG antibodies were collected from SARS-CoV-2 vaccinated or unvaccinated children with no evidence of prior novel coronavirus infection. Chemiluminescence immunoassay was utilized for the in vitro determination of SARS-CoV-2 antibodies. Results: A total of 3,321 healthy children aged 6-11 years received two doses of inactivated SARS-CoV-2 vaccine. At 1 month after the second dose, the positive rate (96.5%) and levels [8.039 (interquartile range (IQR), 6.067-9.098)] of SARS-CoV-2 IgG antibodies reached the peak and remained at a high level for 2-3 months, after which the positive rate and level of vaccine-induced IgG antibody gradually decreased. Compared with 1 month after the second dose of vaccine, the positive rate of IgG antibody decreased to 70.4% at 7 months, and the antibody level decreased by 69.0%. A total of 945 children aged 3-5 years received one or two doses of inactivated vaccine. The positive rate and levels of SARS-CoV-2 IgG antibody in participants remained high for 3 months after vaccination. There was no gender-based difference in positive rate of IgG antibody in children aged 3-11 years old (P>0.05). Among the 5,309 unvaccinated children aged 0 day to 11 years, 105 (2.0%) were positive for SARS-CoV-2 IgG antibody, which was associated with passive infusion. The maternal humoral response to COVID-19 vaccination in noninfected pregnant women was transferred through the placenta to the fetus, and some children obtained SARS-CoV-2-positive antibodies through blood transfusion. Conclusions: Inactivated SARS-CoV-2 vaccines could induce robust humoral immune response that gradually declined within several months after the second dose. Therefore, it helps to determine whether children receive a booster dose and elicit a long-term memory immune response. Positive SARS-CoV-2 antibodies in unvaccinated children were associated with passive IgG antibody infusion.


Subject(s)
COVID-19 Vaccines , COVID-19 , Pregnancy , Humans , Child , Female , Child, Preschool , Seroepidemiologic Studies , Retrospective Studies , SARS-CoV-2 , COVID-19/epidemiology , COVID-19/prevention & control , Antibodies, Viral , Immunoglobulin G , Vaccination
9.
BMJ Open ; 12(11): e066653, 2022 11 21.
Article in English | MEDLINE | ID: covidwho-2137793

ABSTRACT

OBJECTIVES: The study aimed to determine the seroprevalence, the fraction of asymptomatic infections, and risk factors of SARS-CoV-2 infections among the Forcibly Displaced Myanmar Nationals (FDMNs). DESIGN: It was a population-based two-stage cross-sectional study at the level of households. SETTING: The study was conducted in December 2020 among household members of the FDMN population living in the 34 camps of Ukhia and Teknaf Upazila of Cox's Bazar district in Bangladesh. PARTICIPANTS: Among 860 697 FDMNs residing in 187 517 households, 3446 were recruited for the study. One individual aged 1 year or older was randomly selected from each targeted household. PRIMARY AND SECONDARY OUTCOME MEASURES: Blood samples from respondents were tested for total antibodies for SARS-CoV-2 using Wantai ELISA kits, and later positive samples were validated by Kantaro kits. RESULTS: More than half (55.3%) of the respondents were females, aged 23 median (IQR 14-35) years and more than half (58.4%) had no formal education. Overall, 2090 of 3446 study participants tested positive for SARS-CoV-2 antibody. The weighted and test adjusted seroprevalence (95% CI) was 48.3% (45.3% to 51.4%), which did not differ by the sexes. Children (aged 1-17 years) had a significantly lower seroprevalence 38.6% (95% CI 33.8% to 43.4%) compared with adults (58.1%, 95% CI 55.2% to 61.1%). Almost half (45.7%, 95% CI 41.9% to 49.5%) of seropositive individuals reported no relevant symptoms since March 2020. Antibody seroprevalence was higher in those with any comorbidity (57.8%, 95% CI 50.4% to 64.5%) than those without (47.2%, 95% CI 43.9% to 50.4%). Multivariate logistic regression analysis of all subjects identified increasing age and education as risk factors for seropositivity. In children (≤17 years), only age was significantly associated with the infection. CONCLUSIONS: In December 2020, about half of the FDMNs had antibodies against SARS-CoV-2, including those who reported no history of symptoms. Periodic serosurveys are necessary to recommend appropriate public health measures to limit transmission.


Subject(s)
COVID-19 , SARS-CoV-2 , Child , Adult , Female , Humans , Male , Seroepidemiologic Studies , Cross-Sectional Studies , Bangladesh/epidemiology , Myanmar/epidemiology , COVID-19/epidemiology , Antibodies, Viral
10.
Sci Data ; 9(1): 727, 2022 11 26.
Article in English | MEDLINE | ID: covidwho-2133502

ABSTRACT

Seroprevalence studies provide useful information about the proportion of the population either vaccinated against SARS-CoV-2, previously infected with the virus, or both. Numerous studies have been conducted in the United States, but differ substantially by dates of enrollment, target population, geographic location, age distribution, and assays used. This can make it challenging to identify and synthesize available seroprevalence data by geographic region or to compare infection-induced versus combined infection- and vaccination-induced seroprevalence. To facilitate public access and understanding, the National Institutes of Health and the Centers for Disease Control and Prevention developed the COVID-19 Seroprevalence Studies Hub (COVID-19 SeroHub, https://covid19serohub.nih.gov/ ), a data repository in which seroprevalence studies are systematically identified, extracted using a standard format, and summarized through an interactive interface. Within COVID-19 SeroHub, users can explore and download data from 178 studies as of September 1, 2022. Tools allow users to filter results and visualize trends over time, geography, population, age, and antigen target. Because COVID-19 remains an ongoing pandemic, we will continue to identify and include future studies.


Subject(s)
COVID-19 , SARS-CoV-2 , Seroepidemiologic Studies , Humans , United States , Vaccination
12.
Enferm Infecc Microbiol Clin (Engl Ed) ; 40(9): 489-494, 2022 11.
Article in English | MEDLINE | ID: covidwho-2130666

ABSTRACT

INTRODUCTION: In order to deal with the current pandemic caused by the novel SARS-CoV-2 coronavirus several serological immunoassays have been recently developed with the objective of being used as a complementary diagnostic tool and to support the RT-PCR technique currently considered the "gold-standard" method. However, these new assays need to be evaluated and validated. The purpose of this study was to assess the performance of five immunoassays (two ELISA and three CLIA assays) and one rapid immunochromatographic test for the detection of anti-SARS-CoV-2 antibodies. METHODS: Five semiquantitative immunoassays (MENARINI®, PALEX®, VIRCLIA®, ROCHE® and SIEMENS®) and one lateral flow rapid test (WONDFO®) were performed. A total of 124 samples were studied. Case serum samples (n=78) were obtained from COVID-19 patients confirmed by real-time RT-PCR/epidemiological-clinical-radiological criteria, and control non-SARS-CoV-2 samples (n=46) belonged to healthy healthcare workers involved in a seroprevalence study. RESULTS: Overall, the tests showed sensitivities around 70-90% and specificities greater than 95%, including the immunochromatographic test. In addition, we observed very good agreements among them, being better for the detection of IgG than for IgM antibodies (Cohen's kappa index of 0.95 for VIRCLIA® IgG with ROCHE®), as well as good diagnostic power of the tests as determined by the ROC curves. CONCLUSIONS: This study demonstrates the proper performance of the different immunoassays in order to be applied in the clinical practice as support in the diagnostic approach and in the development of vaccines and seroepidemiological studies of COVID-19.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , COVID-19/diagnosis , Seroepidemiologic Studies , Immunoglobulin G , Sensitivity and Specificity , Antibodies, Viral , Immunoassay/methods , Chromatography, Affinity
13.
Clin Lab Med ; 42(1): 31-56, 2022 03.
Article in English | MEDLINE | ID: covidwho-2130425

ABSTRACT

The coronavirus disease of 2019 (COVID-19) pandemic, caused by infection with the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has undoubtedly resulted in significant morbidities, mortalities, and economic disruptions across the globe. Affordable and scalable tools to monitor the transmission dynamics of the SARS-CoV-2 virus and the longevity of induced antibodies will be paramount to monitor and control the pandemic as multiple waves continue to rage in many countries. Serologic assays detect humoral responses to the virus, to determine seroprevalence in target populations, or induction of antibodies at the individual level following either natural infection or vaccination. With multiple vaccines rolling out globally, serologic assays to detect anti-SARS-CoV-2 antibodies will be important tools to monitor the development of herd immunity. To address this need, serologic lateral flow assays (LFAs), which can be easily implemented for both population surveillance and home use, will be vital to monitor the evolution of the pandemic and inform containment measures. Such assays are particularly important for monitoring the transmission dynamics and durability of immunity generated by natural infections and vaccination, particularly in resource-limited settings. In this review, we discuss considerations for evaluating the accuracy of these LFAs, their suitability for different use cases, and implementation opportunities.


Subject(s)
COVID-19 , Antibodies, Viral , Humans , Pandemics , SARS-CoV-2 , Seroepidemiologic Studies
14.
J Med Life ; 15(9): 1119-1128, 2022 Sep.
Article in English | MEDLINE | ID: covidwho-2146200

ABSTRACT

The SARS-CoV-2 pandemic has changed lives around the world. In particular, healthcare workers faced significant challenges as a result of the pandemic. This study investigates the seroprevalence of SARS-CoV-2 in March-April 2020 in Germany among healthcare workers and relates it to questionnaire data. In June 2020, all employees of the reporting hospital were offered a free SARS-CoV-2 antibody test. The first 2,550 test results were sent along with study documents. The response rate was 15.1%. The COVID-19 PCR test prevalence amongst health care workers in this study was 1.04% (95% CI 0.41-2.65%), higher by a factor of 5 than in the general population (p=0.01). The ratio of seroprevalence to PCR prevalence was 1.5. COVID-19-associated symptoms were also prevalent in the non-COVID-19-positive population. Only two symptoms showed statistically significant odds ratios, loss of smell and loss of taste. Health care workers largely supported non-pharmaceutical interventions during the initial lockdown (93%). Individual behavior correlated significantly with attitudes toward policy interventions and perceived individual risk factors. Our data suggest that healthcare workers may be at higher risk of infection. Therefore, a discussion about prioritizing vaccination makes sense. They also support offering increased SARS-CoV-2 testing to hospital workers. It is concluded that easier access to SARS-CoV-2 testing reduces the number of unreported cases. Furthermore, individual attitudes toward rules and regulations on COVID-19 critically influence compliance. Thus, one goal of public policy should be to maintain high levels of support for non-pharmaceutical interventions to keep actual compliance high.


Subject(s)
COVID-19 , Pandemics , Humans , COVID-19/epidemiology , Seroepidemiologic Studies , Prevalence , COVID-19 Testing , SARS-CoV-2 , Communicable Disease Control , Hospitals, University , Personnel, Hospital , Surveys and Questionnaires
15.
Int J Infect Dis ; 111: 190-195, 2021 Oct.
Article in English | MEDLINE | ID: covidwho-2113679

ABSTRACT

BACKGROUND: A number of estimates of the infection fatality ratio (IFR) of SARS-CoV-2 in different countries have been published. In Brazil, the fragile political situation, together with socioeconomic and ethnic diversity, could result in substantially different IFR estimates. METHODS: We infer the IFR in Brazil in 2020 by combining three datasets. We compute the prevalence via the population-based seroprevalence survey, EPICOVID19-BR. For the fatalities we obtain the absolute number using the public Painel Coronavírus dataset and the age-relative number using the public SIVEP-Gripe dataset. The time delay between the development of antibodies and subsequent fatality is estimated via the SIVEP-Gripe dataset. We obtain the IFR for each survey stage and 27 federal states. We include the effect of fading IgG antibody levels by marginalizing over the test detectability time window. RESULTS: We infer a country-wide average IFR (maximum posterior and 95% CI) of 1.03% (0.88-1.22%) and age-specific IFRs of 0.032% (0.023-0.041%) [< 30 years], 0.22% (0.18-0.27%) [30-49 years], 1.2% (1.0-1.5%) [50-69 years], and 3.0% (2.4-3.9%) [≥ 70 years]. We find that the fatality ratio in the country increased significantly at the end of June 2020, likely due to the increased strain on the health system. CONCLUSIONS: Our IFR estimate is based on data and does not rely on extrapolating models. This estimate sets a baseline value with which future medications and treatment protocols may be confronted.


Subject(s)
COVID-19 , Adult , Aged , Bayes Theorem , Brazil/epidemiology , Humans , Middle Aged , SARS-CoV-2 , Seroepidemiologic Studies , Surveys and Questionnaires
16.
Int J Infect Dis ; 111: 336-346, 2021 Oct.
Article in English | MEDLINE | ID: covidwho-2113677

ABSTRACT

BACKGROUND: Understanding the dynamics of the COVID-19 pandemic and evaluating the efficacy of control measures requires knowledge of the number of infections over time. This number, however, often differs from the number of confirmed cases because of a large fraction of asymptomatic infections and different testing strategies. METHODS: This study uses death count statistics, age-dependent infection fatality risks, and stochastic modeling to estimate the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections among adults (aged 20 years or older) in 165 countries over time, from early 2020 until June 25, 2021. The accuracy of the approach is confirmed through comparison with previous nationwide seroprevalence surveys. RESULTS: The estimates presented reveal that the fraction of infections that are detected vary widely over time and between countries, and hence confirmed cases alone often yield a false picture of the pandemic. As of June 25, 2021, the nationwide cumulative fraction of SARS-CoV-2 infections (cumulative infections relative to population size) was estimated as 98% (95% confidence interval [CI] 93-100%) for Peru, 83% (95% CI 61-94%) for Brazil, and 36% (95% CI 23-61%) for the United States. CONCLUSIONS: The time-resolved estimates presented expand the possibilities to study the factors that influenced and still influence the pandemic's progression in 165 countries.


Subject(s)
COVID-19 , SARS-CoV-2 , Adult , Asymptomatic Infections , Humans , Pandemics , Seroepidemiologic Studies , United States , Young Adult
17.
Int J Infect Dis ; 111: 179-185, 2021 Oct.
Article in English | MEDLINE | ID: covidwho-2113609

ABSTRACT

BACKGROUND: Ethiopia reported the first case of COVID-19 on 13th March, 2020 with community transmission ensuing by mid-May. A national, population-based serosurvey against anti-SARS-CoV-2 IgG was conducted to measure the prevalence of prior COVID-19 infections and better approximate the burden across major towns in Ethiopia. METHODS: We conducted a cross-sectional, population-based serosurvey from June 24 to July 8, 2020 in 14 major urban areas. Two-stage cluster sampling was used to randomly select enumeration areas and households. All persons aged ≥15 years were enrolled. Serum samples were tested by Abbott™ ARCHITECT™ assay for SARS-CoV-2 IgG antibodies. National COVID-19 surveillance data on the median date of the serosurvey is analyzed for comparison. FINDINGS: Adjusted seroprevalence was 3.5% (95% CI: 3.2%-3.8%) after controlling for age, sex and test kit performance. Males (3.7%) and females (3.3%) were nearly equally infected, while middle-aged adults '40-65 years' had the highest (4.0%) prevalence. Gambella (7.5%), Dire Dawa (6.2%) and Jigjiga (6.1%) were the most affected towns. About 6.7% and 8.0% of seropositives had symptoms and chronic underlying illness, respectively. A surveillance system had identified 4,416 RT-PCR confirmed cases in Addis Ababa. INTERPRETATION: This serosurvey shows that a majority of urban Ethiopians remain uninfected with SARS-CoV-2. Most anti-SARS-CoV-2 IgG positive cases were asymptomatic with no underlying illness, keeping case detection to a minimum.


Subject(s)
COVID-19 , SARS-CoV-2 , Adolescent , Adult , Aged , Cross-Sectional Studies , Ethiopia/epidemiology , Female , Humans , Male , Middle Aged , Risk Factors , Seroepidemiologic Studies
18.
Viruses ; 14(11)2022 Nov 11.
Article in English | MEDLINE | ID: covidwho-2110275

ABSTRACT

While some companion animals have been shown to be susceptible to SARS-CoV-2, their role in the COVID-19 pandemic has remained poorly investigated. Equids are susceptible to SARS-CoV-2 based on the similarity of the human ACE-2 receptor and reports of infection. Clinical disease and prevalence factors associated with SARS-CoV-2 infection in equids have not yet been investigated. The aim of this study was to determine the seroprevalence of SARS-CoV-2 and selected prevalence factors in 1186 equids presented for various conditions to a Veterinary Medical Teaching Hospital over a two-year period. Blood samples were tested for SARS-CoV-2 antibodies using an ELISA targeting the receptor binding domain (RBD) of the SARS-CoV-2 spike protein. Further, selected prevalence factors (season, age, breed, sex, presenting complaint) were retrieved from the medical records. No information was available on whether the horses had come into contact with COVID-19-positive individuals. Among the study animals, 42/1186 (3.5%) horses had detectable SARS-CoV-2 antibodies. Amongst the prevalence factors investigated, only seasonality (spring) was associated with a greater frequency of seropositivity to SARS-CoV-2. Horses with medical and surgical complaints were more likely to test seropositive to SARS-CoV-2 compared to horses presented for routine health care procedures, suggesting more frequent and/or longer interactions with individuals with COVID-19. While horses can become infected with SARS-CoV-2 via the occasional spillover from COVID-19 individuals, clinical disease expression remains subclinical, making horses an unlikely contributor to the spread of SARS-CoV-2.


Subject(s)
COVID-19 , SARS-CoV-2 , Animals , Antibodies, Viral , California , COVID-19/epidemiology , COVID-19/veterinary , Horses/virology , Hospitals, Teaching , Pandemics , Seroepidemiologic Studies , Hospitals, Animal
19.
Sci Rep ; 12(1): 19492, 2022 Nov 14.
Article in English | MEDLINE | ID: covidwho-2119364

ABSTRACT

Pre-vaccine SARS-CoV-2 seroprevalence data from Germany are scarce outside hotspots, and socioeconomic disparities remained largely unexplored. The nationwide representative RKI-SOEP study (15,122 participants, 18-99 years, 54% women) investigated seroprevalence and testing in a supplementary wave of the Socio-Economic-Panel conducted predominantly in October-November 2020. Self-collected oral-nasal swabs were PCR-positive in 0.4% and Euroimmun anti-SARS-CoV-2-S1-IgG ELISA from dry-capillary-blood antibody-positive in 1.3% (95% CI 0.9-1.7%, population-weighted, corrected for sensitivity = 0.811, specificity = 0.997). Seroprevalence was 1.7% (95% CI 1.2-2.3%) when additionally correcting for antibody decay. Overall infection prevalence including self-reports was 2.1%. We estimate 45% (95% CI 21-60%) undetected cases and lower detection in socioeconomically deprived districts. Prior SARS-CoV-2 testing was reported by 18% from the lower educational group vs. 25% and 26% from the medium and high educational group (p < 0.001, global test over three categories). Symptom-triggered test frequency was similar across educational groups. Routine testing was more common in low-educated adults, whereas travel-related testing and testing after contact with infected persons was more common in highly educated groups. This countrywide very low pre-vaccine seroprevalence in Germany at the end of 2020 can serve to evaluate the containment strategy. Our findings on social disparities indicate improvement potential in pandemic planning for people in socially disadvantaged circumstances.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Adult , Female , Male , Seroepidemiologic Studies , COVID-19 Testing , Travel , COVID-19/diagnosis , COVID-19/epidemiology , Travel-Related Illness , Antibodies, Viral , Immunoglobulin G
20.
PLoS One ; 17(11): e0277764, 2022.
Article in English | MEDLINE | ID: covidwho-2119258

ABSTRACT

The Sentinel Schools project was designed to monitor and evaluate the epidemiology of COVID-19 in Catalonia, gathering evidence for health and education policies to inform the development of health protocols and public health interventions to control of SARS-CoV-2 infection in schools. The aim of this study was to estimate the prevalence and incidence of SARS-CoV-2 infections and to identify their determinants among students and staff during February to June in the academic year 2020-2021. We performed two complementary studies, a cross-sectional and a longitudinal component, using a questionnaire to collect nominal data and testing for SARS-CoV-2 detection. We describe the results and perform a univariate and multivariate analysis. The initial crude seroprevalence was 14.8% (95% CI: 13.1-16.5) and 22% (95% CI: 18.3-25.8) for students and staff respectively, and the active infection prevalence was 0.7% (95% CI: 0.3-1) and 1.1% (95% CI: 0.1-2). The overall incidence for persons at risk was 2.73 per 100 person-month and 2.89 and 2.34 per 100 person-month for students and staff, respectively. Socioeconomic, self-reported knowledge, risk perceptions and contact pattern variables were positively associated with the outcome while sanitary measure compliance was negatively associated, the same significance trend was observed in multivariate analysis. In the longitudinal component, epidemiological close contact with SARS-CoV-2 infection was a risk factor for SARS-CoV-2 infection while the highest socioeconomic status level was protective as was compliance with sanitary measures. The small number of active cases detected in these schools suggests a low transmission among children in school and the efficacy of public health measures implemented, at least in the epidemiological scenario of the study period. The major contribution of this study was to provide results and evidence that help analyze the transmission dynamic of SARS-CoV-2 and evaluate the associations between sanitary protocols implemented, and measures to avoid SARS-CoV-2 spread in schools.


Subject(s)
COVID-19 , Child , Humans , COVID-19/epidemiology , Prevalence , Incidence , Seroepidemiologic Studies , Cross-Sectional Studies , Spain/epidemiology , SARS-CoV-2 , Schools
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