Prevalence of SARS-CoV-2 infection in India: Findings from the national serosurvey, May-June 2020
Indian Council of Medical Research1, All India Institute of Medical Sciences2, Regional Medical Research Centre3, Government Medical College, Srinagar4, Rajendra Memorial Research Institute of Medical Sciences5, Government of Karnataka6, National Institute of Occupational Health7, National Institute of Virology8, National Tuberculosis Institute9, National Centre for Disease Control10
TL;DR: Seroprevalence of SARS-CoV-2 was low among the adult population in India around the beginning of May 2020, and males, living in urban slums and occupation with high risk of exposure to potentially infected persons were associated with seropositivity.
Abstract: Background & objectives: Population-based seroepidemiological studies measure the extent of SARS-CoV-2 infection in a country. We report the findings of the first round of a national serosurvey, conducted to estimate the seroprevalence of SARS-CoV-2 infection among adult population of India. Methods: From May 11 to June 4, 2020, a randomly sampled, community-based survey was conducted in 700 villages/wards, selected from the 70 districts of the 21 States of India, categorized into four strata based on the incidence of reported COVID-19 cases. Four hundred adults per district were enrolled from 10 clusters with one adult per household. Serum samples were tested for IgG antibodies using COVID Kavach ELISA kit. All positive serum samples were re-tested using Euroimmun SARS-CoV-2 ELISA. Adjusting for survey design and serial test performance, weighted seroprevalence, number of infections, infection to case ratio (ICR) and infection fatality ratio (IFR) were calculated. Logistic regression was used to determine the factors associated with IgG positivity. Results: Total of 30,283 households were visited and 28,000 individuals were enrolled. Population-weighted seroprevalence after adjusting for test performance was 0.73 per cent [95% confidence interval (CI): 0.34-1.13]. Males, living in urban slums and occupation with high risk of exposure to potentially infected persons were associated with seropositivity. A cumulative 6,468,388 adult infections (95% CI: 3,829,029-11,199,423) were estimated in India by the early May. The overall ICR was between 81.6 (95% CI: 48.3-141.4) and 130.1 (95% CI: 77.0-225.2) with May 11 and May 3, 2020 as plausible reference points for reported cases. The IFR in the surveyed districts from high stratum, where death reporting was more robust, was 11.72 (95% CI: 7.21-19.19) to 15.04 (9.26-24.62) per 10,000 adults, using May 24 and June 1, 2020 as plausible reference points for reported deaths. Interpretation & conclusions: Seroprevalence of SARS-CoV-2 was low among the adult population in India around the beginning of May 2020. Further national and local serosurveys are recommended to better inform the public health strategy for containment and mitigation of the epidemic in various parts of the country.
Citations
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TL;DR: In this article, a systematic review and meta-analysis of serological surveys for antibodies to SARS-CoV-2 have been reported worldwide, and the authors aimed to synthesise, combine, and assess this large corpus of data.
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TL;DR: In this paper, a Bayesian model explains the growth advantage of Delta through a combination of increased transmissibility and reduced sensitivity to immune responses generated against earlier variants (median estimates; ×1.5-fold, 20% reduction).
Abstract: Delhi, the national capital of India, has experienced multiple SARS-CoV-2 outbreaks in 2020 and reached population seropositivity of over 50% by 2021. During April 2021, the city became overwhelmed by COVID-19 cases and fatalities, as a new variant B.1.617.2 (Delta) replaced B.1.1.7 (Alpha). A Bayesian model explains the growth advantage of Delta through a combination of increased transmissibility and reduced sensitivity to immune responses generated against earlier variants (median estimates; ×1.5-fold, 20% reduction). Seropositivity of an employee and family cohort increased from 42% to 87.5% between March and July 2021, with 27% reinfections, as judged by increased antibody concentration after a previous decline. The likely high transmissibility and partial evasion of immunity by the Delta variant contributed to an overwhelming surge in Delhi.
165 citations
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Indian Council of Medical Research1, National Institute of Occupational Health2, Regional Medical Research Centre3, Government Medical College, Srinagar4, National Institute of Nutrition, Hyderabad5, Rajendra Memorial Research Institute of Medical Sciences6, National Tuberculosis Institute7, Government of Karnataka8
TL;DR: A second household serosurvey among individuals aged 10 years or older in the same 700 villages or wards within 70 districts in India that were included in the first sero-survey was conducted in this article.
143 citations
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TL;DR: In this paper, the authors evaluated the risk of SARS-CoV-2 re-infections in the general population in Austria by tracking polymerase chain reaction (PCR)-confirmed infections of both groups during the second wave from September 1 to November 30, 2020.
Abstract: Background A key question concerning coronavirus disease 2019 (COVID-19) is how effective and long lasting immunity against this disease is in individuals who were previously infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We aimed to evaluate the risk of SARS-CoV-2 re-infections in the general population in Austria. Methods This is a retrospective observational study using national SARS-CoV-2 infection data from the Austrian epidemiological reporting system. As the primary outcome, we aim to compare the odds of SARS-CoV-2 re-infections of COVID-19 survivors of the first wave (February to April 30, 2020) versus the odds of first infections in the remainder general population by tracking polymerase chain reaction (PCR)-confirmed infections of both groups during the second wave from September 1 to November 30, 2020. Re-infection counts are tentative, since it cannot be excluded that the positive PCR in the first and/or second wave might have been a false positive. Results We recorded 40 tentative re-infections in 14 840 COVID-19 survivors of the first wave (0.27%) and 253 581 infections in 8 885 640 individuals of the remaining general population (2.85%) translating into an odds ratio (95% confidence interval) of 0.09 (0.07 to 0.13). Conclusions We observed a relatively low re-infection rate of SARS-CoV-2 in Austria. Protection against SARS-CoV-2 after natural infection is comparable with the highest available estimates on vaccine efficacies. Further well-designed research on this issue is urgently needed for improving evidence-based decisions on public health measures and vaccination strategies.
106 citations
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TL;DR: It is suggested that SARS-CoV2-specific IgG or IgM seroconversion occurs within 20 days post symptom onset and may be helpful for the diagnosis of suspected patients with negative RT–PCR results and for the identification of asymptomatic infections.
Abstract: We report acute antibody responses to SARS-CoV-2 in 285 patients with COVID-19. Within 19 days after symptom onset, 100% of patients tested positive for antiviral immunoglobulin-G (IgG). Seroconversion for IgG and IgM occurred simultaneously or sequentially. Both IgG and IgM titers plateaued within 6 days after seroconversion. Serological testing may be helpful for the diagnosis of suspected patients with negative RT-PCR results and for the identification of asymptomatic infections.
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10 Mar 2020
2,024 citations
"Prevalence of SARS-CoV-2 infection ..." refers background in this paper
...Based on the overall adjusted seroprevalence of 0.73 per cent and reported number of COVID-19 cases, it was estimated that for every RT-qPCR confirmed case of COVID-19, there were 82-130 infections in India....
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...The seroprevalence of 0.73 per cent was estimated assuming that the two tests are completely independent....
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TL;DR: The majority of the Spanish population is seronegative to SARS-CoV-2 infection, even in hotspot areas, and results emphasise the need for maintaining public health measures to avoid a new epidemic wave.
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