The seroprevalence and trends of SARS-CoV-2 in Delhi, India: A repeated population-based seroepidemiological study

Abstract

BackgroundThree rounds of a repeated cross-sectional serosurvey to estimate the seroprevalence and trends of SARS-CoV-2 were conducted from August-October’ 2020 in the state of Delhi in India in the general population aged ≥5 years.MethodsThe selection of participants was through a multi-stage sampling design from all the 11 districts and 280 wards of the city-state, with two-stage allocation proportional to population- size. Household selected was via systematic random sampling, and individual participant selection through the age-order procedure. The blood samples were screened using the IgG ELISA COVID-Kawach kit (August Round), and the ERBALISA COVID-19 IgG (September and October) rounds. The seroprevalence was estimated by applying the sampling weights based on age and sex with further adjustment for the assay-kit characteristics.ResultsA total of 4267 (n=15046), 4311 (n=17409), and 3829 (n=15015) positive tests indicative of the presence of IgG antibody to SARS-CoV-2 were observed during the August, September, and October 2020 serosurvey rounds, respectively. The adjusted seroprevalence declined from 28.39% (95% CI 27.65-29.14) (August) to 24.08% (95% CI 23.43-24.74) (September), and 24.71% (95% CI 24.01, 25.42%) (October). The antibody positivity was highest in the ≥50 and female age-group during all rounds of the serosurvey, while the decline was maximum among the younger age-group (5-17 years). On adjusted analysis, participants with lower per capita income, living in slums or overcrowded households, and those with diabetes comorbidity had significantly higher statistical odds of antibody positivity.ConclusionsDespite high IgG seroprevalence, there was evidence for waning of antibody positivity with the progression of the COVID-19 epidemic, implying a potential reduction in population immunity, especially if also associated with the lack of trained T cell immunity.

Seroprevalence of SARS-CoV-2 in Bhubaneswar, India: findings from three rounds of community surveys

“…Similar to our study, a recent evaluation of seroprevalence of SARS-CoV-2 antibodies among a population in Delhi revealed the highest antibody positivity among women ≥50 years of age [23].…”

“…Although the three phases of serosurveys carried out in the city of Bhubaneswar, India, show an increasing trend of seropositivity, it [15,16]. Similar trends have also been reported in serosurveys from the UK [17].…”

Serological evidence of human infection with SARS-CoV-2: a systematic review and meta-analysis

“…Values higher than 1 suggest greater under-reporting of infections (due to both mild or asymptomatic infections, care-seeking behaviours, and testing practices). 27 USA, California, Marin (Appa et al 2020) 28 USA, California, Orange (Bruckner et al 2021) 29 USA, Connecticut (Mahajan et al 2020) 30 USA, Georgia, DeKalb and Fulton (Biggs et al 2020) 31 USA, Idaho, Blaine (McLaughlin et al 2020) 32 USA, Utah, four counties (Samore et al 2020) 33 Denmark, Faroe Islands (Petersen et al 2020) 34 Germany, Kreis Heinsberg, Gangelt (Streeck et al 2020) 35 Luxembourg (Snoeck et al 2020) 36 Netherlands (Vos et al 2020) 37 Russia, Saint Petersburg (Barchuk et al 2020) 38 Spain (Pollán et al 2020) 39 Switzerland, Geneva (Richard et al 2020) 40 Switzerland, Geneva (Stringhini et al 2020) 41 UK, England (Office of National Statistics 2020) 42 UK, England (Ward et al 2020) 43 UK, Jersey (Government of Jersey 2020) 44 India (Murhekar et al 2020 ) 45 India (Murhekar et al 2021) 46 India, Delhi (Sharma et al 2020) 47 India, Mumbai (Malani et might lead to mis-specification of assay performance. 53 Notably, although WHO has established a generic population-based serological study protocol, standardised guidelines and procedures for laboratory testing are scarce, which might contribute towards such heterogeneity in performance and reporting of results.…”

“…63 We found a pooled seroprevalence of 8•0% in the general population, suggesting that globally, the number of people infected by the end of 2020 was unlikely to satisfy estimates of what it would take to achieve antibody-mediated herd immunity. 39,41,64 The seroprevalence in the general population also varied across WHO regions, with a higher prevalence of SARS-CoV-2specific anti bodies in the South-East Asia region (eg, India, range: 10•8-40•8%) [46][47][48] contrasting with a relatively lower seroprevalence in the Western Pacific region (eg, China, range: 0•8-3•3%), 65,66 indicating different levels of community transmission of SARS-CoV-2 in different locales, potentially due to differences in non-pharmaceutical interventions. 67 Additionally, the very limited number of high-quality studies in all but two of the WHO regions underlines our incomplete under standing of SARS-CoV-2 transmission in much of the world.…”

Is Covid-19 seroprevalence different in health care workers as per their risk of exposure? A study from a tertiary care hospital in National Capital Region of India

“…Indian data from two metropolitan studies (Srinagar and Kolkata) show a variation in the prevalence in health care workers ranging from 0.6% to 11.94% [10][11]. Seroprevalence in our study was high at 46.2% (CI 44.4 -47.9%), this might be due to the changing profile of the seroprevalence in the community from 24.71 % in October 2020 [30] to more than 50% as per Delhi government fifth serosurvey conducted in January, 2021 or due to higher risk of exposure to Covid-19 patients due to the nature of the hospital (focused Covid care hospital). Seroprevalence was significantly lower in clinical HCW (41.4%) as compared to non-clinical HCW workers (50.2%) (p = 0.0001).…”