Assessing seropositivity for IgG antibodies against SARS-CoV-2 in Ahmedabad city of India: a cross-sectional study

Seroprevalence of SARS-CoV-2 in hospital workers in the southern region of Minas Gerais state in Brazil: An analysis of the pre-vaccine period

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection seroprevalence can be performed by detecting anti-SARS-CoV-2 antibodies. The survey is essential to understand the disease transmission's dynamic in the studied population. This study aimed to carry out a seroepidemiological survey of SARS-CoV-2 in three hospitals located in the south of Minas Gerais state, Brazil. 859 samples were collected from August to December 2020 when SARS-CoV-2 vaccines were still not available and Enzyme-linked immunosorbent assays (ELISA) were performed on participants sera. The average age of participants was 38 years, and most were women (71.4%). Likewise, most participants were classified as health professionals with direct or indirect contact with patients with COVID-19 (74.5%). The other participants tested belonged to other sectors, such as the administrative one (11,6%). Considering clinical symptoms, 15.8% of participants reported diarrhoea, 6.4% fever, 5.8% respiratory distress, and 7.0% loss of smell and taste. Many participants reported contact with infected patients (63.35%). Regarding the ELISA tests, 21.6% of the participants had positive results and hospital 3 had the highest positivity (21.7%), followed by hospital 2 (21.6%) and hospital 1 (20.3%). The prevalence was higher in women compared to men (22,8% and 18,7%, respectively). Regarding the area of expertise, the highest positivity (20.9%) was observed among health professionals. However, professionals who worked exclusively with COVID-19 had lower positivity when compared to professionals who did not work directly with COVID-19 (22.0% and 21.5%, respectively). When analysing the correlation between the ELISA tests with the other variables, a significant association was detected with these previous serological variables, previous contact with COVID-19 and the presence of fever symptoms, loss of smell and taste. Clinical symptoms associated with serological tests are important tools for monitoring the disease among health professionals.

Measles seroprevalence in persons over one year of age in Chandigarh, India

Measles continues to result in focal outbreaks in India, despite over three decades of universal infant vaccination. The aims of this study were to examine measles immunity in the population of Chandigarh, India, and to compare immunity by vaccination vs. natural infection. In a cross-sectional study of individuals 1-60 years selected from 30 communities within Chandigarh during 2017-2018, measles immunity was assessed using serological surveys. Seropositivity was compared across demographic groups, and by prior history of vaccination and natural history of infection. Among those 1-20 years old, measles seropositivity, and histories of measles vaccination or prior measles diagnosis were separately assessed as outcomes in logistic regression models, with demographic factors as independent variables. Among 1690 participants, 94% were seropositive, and 6% had borderline or negative antibody levels. Of those positive, 30% had prior vaccination, 16% had a history of natural infection, and 54% had an unknown history. Over 50% of individuals among those >20 years old, had unknown history of immunity. In the multivariable regression models, vaccination was more common in younger ages (P < .0001), and in males compared to females (P = .0220), and in those with more education (P < .0001). The majority of the population was seropositive, and seropositivity increased with age. Older age groups were more likely to be protected because of previous natural infection, whereas younger age groups were protected by vaccination. There was inequity in vaccination coverage by gender, and maternal education status.

COVID-Kavach-Based Seropositivity in the General Population of Ahmedabad: Just Before the Start of the Vaccination for the Elderly in India

Background

The present study was carried out in succession of three serosurvey studies carried out during 2020 in Ahmedabad with an objective to estimate the seroprevalence of immunoglobulin G (IgG) antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) in Ahmedabad city so as to scientifically understand the pandemic progression.

Methods

Polio booth-based stratification was followed for the population-based stratified sampling among the general population of Ahmedabad. The seroprevalence was compared with various factors for valid and precise predictions regarding the immunity status of the population.

Results

As on February 2021, the seroprevalence for IgG antibodies against SARS-CoV2 in the general population of Ahmedabad was 27.92% (95% confidence interval 27.06-28.80), much below the minimum desired for herd immunity. Comparison of seropositivity with age groups showed higher seroprevalence with increasing age groups. Seroprevalence was higher among males (29.08%) than females (27.01%) and the difference was statistically significant (Z=2.30, P=0.02). Calculating the seropositivity among the subcategories, cases had a seropositivity of 64.90% and family contacts had a seropositivity of 28.00%. Seronegative cases indicate the possibility of absent, undetectable, or disappearing IgG antibodies. Seropositivity of 37% among the vaccinated individuals may be related to dose and duration of vaccination, as the COVID vaccination had started just before the present study and none had completed 14 days after the second dose.

Conclusions

The low level of IgG antibodies against SARS-CoV2 using the COVID-Kavach test kit in the general population of Ahmedabad city of India, as on February 2021, before the start of COVID vaccination for the general population suggests that the preventive measures be strongly followed for continued control of the pandemic situation at least till majority of the population is effectively covered with vaccination.

Covid-19 Serosurveillance Positivity in General Population: Comparison at Different Times

Introduction: Serological surveys estimating the cumulative incidence of the disease are powerful and effective tools for monitoring the epidemic and in determining the immunity status. Objectives: To compare the percentage sero-positivity for IgG antibodies against SARS-CoV2 at two different time period in the same population to understand the pandemic and predict about the immunity status of the population. Methods: As a part of Covid19 pandemic management, two separate population based sero-survey within a gap of 1½ months were carried in Ahmedabad city to scientifically document the progress of the Covid19 pandemic. Various demographic factors and other parameters from both the survey were compared with seropositivity for valid and precise estimation of disease situation as well as immunity status of the population. Results: The study documents an increase in seropositivity by 5.32% (from 17.92% to 23.24%). The seropositivity shows increasing trend with increase in the age group and the seropositivity is significantly higher among females. Overall higher seropositivity against the reported cases in the first sero-survey and the narrow increase in the seropositivity during the subsequent sero-survey inspite of high number of cases may indicate temporary status of the antibodies. This may also be due to the difference in the level of stigma, health care service delivery, service utilization and related field level situation affecting the asymptomatic/unreported case positivity. Conclusion: The result of seropositivity comparison indicates the scopes for further research to confirm and generate greater evidences regarding the factors affecting seropositivity.

SARS-CoV-2 seroprevalence in the city of Hyderabad, India in early 2021

Background

COVID-19 emerged as a global pandemic in 2020, spreading rapidly to most parts of the world. The proportion of infected individuals in a population can be reliably estimated via serosurveillance, making it a valuable tool for planning control measures. Our serosurvey study aimed to investigate SARS-CoV-2 seroprevalence in the urban population of Hyderabad at the end of the first wave of infections.

Methods

This cross-sectional survey, conducted in January 2021 and including males and females aged 10 years and above, used multi-stage random sampling. 9363 samples were collected from 30 wards distributed over six zones of Hyderabad, and tested for antibodies against SARS-CoV-2 nucleocapsid antigen.

Results

Overall seropositivity was 54.2%, ranging from 50% to 60% in most wards. Highest exposure appeared to be among those aged 30–39 and 50–59 years, with women showing greater seropositivity. Seropositivity increased with family size, with only marginal differences among people with varying levels of education. Seroprevalence was significantly lower among smokers. Only 11% of the survey subjects reported any COVID-19 symptoms, while 17% had appeared for COVID-19 testing.

Conclusion

Over half the city's population was infected within a year of onset of the pandemic. However, ∼ 46% of people remained susceptible, contributing to subsequent waves of infection.

Seroprevalence of IgG antibodies against SARS-CoV-2 in India, March 2020 to August 2021: a systematic review and meta-analysis

INTRODUCTION

India experienced 2 waves of COVID-19 pandemic caused by SARS-CoV-2 and reported the second highest caseload globally. Seroepidemiologic studies were done to track the course of the pandemic. We systematically reviewed and synthesized the seroprevalence of SARS-CoV-2 in the Indian population.

METHODS

We included studies reporting seroprevalence of IgG antibodies against SARS-CoV-2 from March 1, 2020 to August 11, 2021 and excluded studies done only among patients with COVID-19 and vaccinated individuals. We searched published databases, preprint servers, and government documents using a combination of keywords and medical subheading (MeSH) terms of "Seroprevalence AND SARS-CoV-2 AND India". We assessed risk of bias using the Newcastle-Ottawa scale, the appraisal tool for cross-sectional studies (AXIS), the Joanna Briggs Institute (JBI) critical appraisal tool, and WHO's statement on the Reporting of Seroepidemiological Studies for SARS-CoV-2 (ROSES-S). We calculated pooled seroprevalence along with 95% Confidence Intervals (CI) during the first (March 2020 to February 2021) and second wave (March to August 2021). We also estimated seroprevalence by selected demographic characteristics.

RESULTS

We identified 3821 studies and included 53 studies with 905379 participants after excluding duplicates, screening of titles and abstracts and full-text screening. Of the 53, 20 studies were of good quality. Some of the reviewed studies did not report adequate information on study methods (sampling = 24% (13/53); laboratory = 83% [44/53]). Studies of 'poor' quality had more than one of the following issues: unjustified sample size, nonrepresentative sample, nonclassification of nonrespondents, results unadjusted for demographics and methods insufficiently explained to enable replication. Overall pooled seroprevalence was 20.7% in the first (95% CI = 16.1 to 25.3) and 69.2% (95% CI = 64.5 to 73.8) in the second wave. Seroprevalence did not differ by age in first wave, whereas in the second, it increased with age. Seroprevalence was slightly higher among women in the second wave. In both the waves, the estimate was higher in urban than in rural areas.

CONCLUSION

Seroprevalence increased by 3-fold between the 2 waves of the pandemic in India. Our review highlights the need for designing and reporting studies using standard protocols.

Review of Clinical Performance of Serology Based Commercial Diagnostic Assays for Detection of Severe Acute Respiratory Syndrome Coronavirus 2 Antibodies

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, which caused the coronavirus disease 2019 (COVID-19) pandemic as declared by the World Health Organization, has created havoc worldwide. The highly transmissible infection can be contained only by accurate diagnosis, quarantining, and exercising social distancing. Therefore, quick and massive deployment of SARS-CoV-2 testing plays a crucial role in the identification and isolation of infected patients. Reverse transcription-polymerase chain reaction is the gold standard for COVID-19 detection; however, it needs expertise, facilities, and time. Hence, for the ease of population-wide screening, serology-based diagnostic assays were introduced. These can help determine the prevalence of infection, understand the epidemiology of the disease, and assist in suitable public health interventions while being user-friendly and less time consuming. Although serological testing kits in markets soared, their sensitivity and specificity were questioned in reports from different parts of the world. In this article, we have reviewed 40 Food and Drug Administration (FDA) and CE-approved clinically evaluated serological kits (8 enzyme-linked immunosorbent assay [ELISA] kits, 10 chemiluminescent immunoassay [CLIA] kits, and 22 lateral flow immunoassay [LFIA] kits) for their sensitivity and specificity and discussed the apparent reasons behind their performance. We observed appreciable sensitivity in the kits detecting total antibodies compared to the kits targeting single isotype antibodies. Tests that determined antibodies against nucleocapsid protein were found to be more sensitive and those detecting antibodies against spike protein were found to have greater specificity. This study was conducted to help the decision-making while acquiring antibody kits and concurrently to be mindful of their shortcomings.

Seroprevalence of SARS-CoV-2 antibodies in Bali Province: Indonesia shows underdetection of COVID-19 cases by routine surveillance

The international tourist destination of Bali reported its first case of Coronavirus Disease 2019 or COVID-19 in March 2020. To better understand the extent of exposure of Bali's 4.3 million inhabitants to the COVID-19 virus, we performed two repeated cross-sectional serosurveys stratified by urban and rural areas. We used a highly specific multiplex assay that detects antibodies to three different viral antigens. We also assessed demographic and social risk factors and history of symptoms. Our results show that the virus was widespread in Bali by late 2020, with 16.73% (95% CI 12.22-21.12) of the population having been infected by that time. We saw no differences in seroprevalence between urban and rural areas, possibly due to extensive population mixing, and similar levels of seroprevalence by gender and among age groups, except for lower seroprevalence in the very young. We observed no difference in seroprevalence between our two closely spaced surveys. Individuals reporting symptoms in the past six months were about twice as likely to be seropositive as those not reporting symptoms. Based upon official statistics for laboratory diagnosed cases for the six months prior to the survey, we estimate that for every reported case an additional 52 cases, at least, were undetected. Our results support the hypothesis that by late 2020 the virus was widespread in Bali, but largely undetected by surveillance.

Immunoglobulin-G Antibodies against Severe Acute Respiratory Syndrome - Coronavirus-2 among Health-Care Workers: A Serosurveillance Study from India

Background:

Seropositivity among health-care workers (HCWs) may help in better understanding of the immune response after COVID-19 infection.

Objectives:

To estimate seropositivity among HCWs and to compare available variables with seropositivity to understand the factors affecting seropositivity.

Materials and Methods:

A serosurveillance among HCWs was carried out using population proportion sampling during the second half of October 2020 in the city of Ahmedabad using the Covid-Kavach (immunoglobulin G [IgG] ELISA Antibody testing kit). Simple proportions and appropriate statistical tests were used as needed.

Results:

As on October' 2020, HCWs in Ahmedabad demonstrated a seropositivity of 20.84% (95% confidence interval [CI] 19.00–22.81%). Seropositivity among HCWs was lower than that of the general population (24.20%) which was estimated as part of the same study. Female HCWs had higher seropositivity 22.14% (95% CI 19.74–24.74%) as compared to 18.82% (95% CI 16.06–21.93%) among male HCWs and the difference was statistically not significant (Z = 1.66, P = 0.097). Age groups with increasing age show increasing trend in the seropositivity among HCWs.

Conclusion:

As on October 2020, with 20.84% seropositivity among HCWs in Ahmedabad, one in every five HCW already demonstrate IgG antibodies against severe acute respiratory syndrome– coronavirus-2. Further scientific studies on seropositivity and the factors affecting the seropositivity may be carried out to uncover more details of immune reaction after COVID-19 infection.

Second round statewide sentinel-based population survey for estimation of the burden of active infection and anti-SARS-CoV-2 IgG antibodies in the general population of Karnataka, India, during January-February 2021

Objective

Demonstrate the feasibility of using the existing sentinel surveillance infrastructure to conduct the second round of the serial cross-sectional sentinel-based population survey. Assess active infection, seroprevalence, and their evolution in the general population across Karnataka. Identify local variations for locally appropriate actions. Additionally, assess the clinical sensitivity of the testing kit used on account of variability of antibody levels in the population.

Methods

The cross-sectional study of 41,228 participants across 290 healthcare facilities in all 30 districts of Karnataka was done among three groups of participants (low, moderate, and high-risk). The geographical spread was sufficient to capture local variations. Consenting participants were subjected to real-time reverse transcription-polymerase chain reaction (RT-PCR) testing, and antibody (IgG) testing. Clinical sensitivity was assessed by conducting a longitudinal study among participants identified as COVID-19 positive in the first survey round.

Results

Overall weighted adjusted seroprevalence of IgG was 15.6% (95% CI: 14.9-16.3), crude IgG prevalence was 15.0% and crude active infection was 0.5%. Statewide infection fatality rate (IFR) was estimated as 0.11%, and COVID-19 burden estimated between 26.1 to 37.7% (at 90% confidence). Further, Cases-to-infections ratio (CIR) varied 3-35 across units and IFR varied 0.04-0.50% across units. Clinical sensitivity of the IgG ELISA test kit was estimated as ≥38.9%.

Conclusion

We demonstrated the feasibility and simplicity of sentinel-based population survey in measuring variations in subnational and local data, useful for locally appropriate actions in different locations. The sentinel-based population survey thus helped identify districts that needed better testing, reporting, and clinical management. The state was far from attaining natural immunity during the survey and hence must step up vaccination coverage and enforce public health measures to prevent the spread of COVD-19.

Seroprevalence of Immunoglobulin-G Antibody Among Confirm Cases of COVID-19

Background

Sero-surveillance to find the presence of IgG antibodies among COVID-19 cases helps in the better understanding of the immune response after COVID-19 infection.

Objectives

To estimate seropositivity among confirmed COVID-19 cases and to correlate the seropositivity with various factors affecting seropositivity.

Methods

Population-based sero-surveillance among COVID-19 cases was carried out during the second half of August 2020 in Ahmedabad using the COVID KAVACH, Immunoglobulin-G (IgG) Antibody Detection Enzyme-Linked Immunosorbent Assay (ELISA) kits. Seropositivity among cases was measured and compared with various other factors to understand the immunity status among COVID-19 cases.

Results

With 1073 positive for IgG antibodies from 1720 samples, the seropositivity among COVID-19 cases is 62.38% [95%CI 60.07-64.64%]. The difference in seropositivity based on gender was statistically not significant (Z=0.26, P=0.79). Children have the highest seropositivity (94.44%) and from young adults, to the elderly, the proportion of positivity among cases shows an increasing trend. Time gap analysis from the date of diagnosis shows that the proportion of cases with IgG antibodies increases gradually reaching its peak at around 10 weeks (third month) and then declines gradually.

Conclusion

Seropositivity among COVID-19 cases is 62.38%. The proportion of cases with IgG antibodies reaches its peak at around 10 weeks (third month) after diagnosis and then declines gradually. This fall indicates that the detected antibodies may not be long-lasting and may become undetectable/absent over a period of time. The reason for seronegative results in COVID-19 cases needs further in-depth scientific research.

Population-based seropositivity for IgG antibodies against SARS-CoV-2 in Ahmedabad city

CONTEXT

Ahmedabad city with approximately 7 million population was one of the earliest cities to witness the high case load of COVID-19 pandemic in India. A population-based sero-survey was ideally suited in Ahmedabad to guide the public health response for managing COVID-19 pandemic.

OBJECTIVES

To study the percentage sero-positivity for SARS-CoV-2 to understand the pandemic status and deriving conclusions for guiding the public health measures for managing the COVID-19 pandemic.

SETTINGS AND DESIGN

Population-based cross-sectional sero-surveillance.

METHODS AND MATERIAL

Large scale sero-surveillance with population-based stratified sampling covering more than 10,000 samples from general population of Ahmedabad was carried out during second half of August 2020. The seropositivity was correlated and compared with various demographic factors and other parameters for valid and precise predictions on the immunity status of the population.

RESULTS

With 2,396 samples positive for IgG antibodies from a total of 10,310 samples, the seropositivity against COVID-19 in the general population of Ahmedabad is around 23.24%. The seropositivity has increasing trend with increasing age and is significantly higher among females (25.37%) than males (21.81%). The zone wise positivity ranged from 11.74% to 33.14%. This closely correlates with the cases recorded so far, higher for those zones with high current or past cases.

CONCLUSIONS

Seropositivity of 23.24% in general population indicate the overall current level of protection. Since effective vaccine is not yet available, it is required to continue emphasis on the public health preventive measures for controlling and managing the COVID-19 pandemic.

Seroprevalence of IgG against SARS-CoV-2 and its determinants among healthcare workers of a COVID-19 dedicated hospital of India

Healthcare workers (HCWs) due to their job profile are at utmost risk of contracting severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Serological survey is an useful tool for vulnerability mapping in an infectious disease pandemic. The aim of the current study was to assess seroprevalence of IgG against SARS-CoV-2 and its determinants among HCWs of a tertiary healthcare facility of India. It was an observational study, cross-sectional in design conducted among 919 HCWs of All India Institute of Medical Sciences, Patna, Bihar, India during September, 2020. In results, IgG seroprevalence for SARS-CoV-2 among the study subjects was 13.3% [95% confidence interval (CI): 11.2-15.6%]. In univariate logistic regression analysis; gender, occupation, place of posting, use of full personal protective equipment (PPE), prior corona virus disease (COVID)-19 infection, influenza like illness (ILI), use of steam inhalation, consumption of azithromycin, zinc and vitamin C were the significant attributes which affected the IgG seropositivity for SARS-CoV-2. In the multivariable logistic regression model; occupation, place of posting, prior COVID-19 infection and ILI were significant determinants of IgG seropositivity for SARS-CoV-2. To conclude, majority of the HCWs were found to be IgG seronegative for SARS-CoV-2. Till availability of effective vaccine all of the HCWs should abide by infection prevention and control (IPC) measures to keep themselves and their contacts protected from SARS-CoV-2.