Background The first national severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serosurvey in India, done in May-June, 2020, among adults aged 18 years or older from 21 states, found a SARS-CoV-2 IgG antibody seroprevalence of 0•73% (95% CI 0•34-1•13). We aimed to assess the more recent nationwide seroprevalence in the general population in India.
MethodsWe did 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 serosurvey. Individuals aged younger than 10 years and households that did not respond at the time of survey were excluded. Participants were interviewed to collect information on sociodemographics, symptoms suggestive of COVID-19, exposure history to laboratoryconfirmed COVID-19 cases, and history of COVID-19 illness. 3-5 mL of venous blood was collected from each participant and blood samples were tested using the Abbott SARS-CoV-2 IgG assay. Seroprevalence was estimated after applying the sampling weights and adjusting for clustering and assay characteristics. We randomly selected one adult serum sample from each household to compare the seroprevalence among adults between the two serosurveys.Findings Between Aug 18 and Sept 20, 2020, we enrolled and collected serum samples from 29 082 individuals from 15 613 households. The weighted and adjusted seroprevalence of SARS-CoV-2 IgG antibodies in individuals aged 10 years or older was 6•6% (95% CI 5•8-7•4). Among 15 084 randomly selected adults (one per household), the weighted and adjusted seroprevalence was 7•1% (6•2-8•2). Seroprevalence was similar across age groups, sexes, and occupations. Seroprevalence was highest in urban slum areas followed by urban non-slum and rural areas. We estimated a cumulative 74•3 million infections in the country by Aug 18, 2020, with 26-32 infections for every reported COVID-19 case.Interpretation Approximately one in 15 individuals aged 10 years or older in India had SARS-CoV-2 infection by Aug 18, 2020. The adult seroprevalence increased approximately tenfold between May and August, 2020. Lower infection-to-case ratio in August than in May reflects a substantial increase in testing across the country.
Background
Earlier serosurveys in India revealed SARS-CoV-2 seroprevalence of 0.73% during May-June and 7.1% during August-September 2020. We conducted the third serosurvey during Dec 2020 and Jan 2021, to estimate the seroprevalence of SARS-CoV-2 infection among general population and healthcare workers (HCWs) in India.
Methods
We conducted the serosurvey in the same 70 districts selected for the first and second serosurveys. From each district, we enrolled at least 400 individuals aged ≥ 10 years from general population and 100 HCWs from sub-district level health facilities. Sera from general population were tested for presence of IgG antibodies against nucleocapsid (N) and spike protein (S1-RBD) of SARS-CoV-2, whereas sera from HCWs were tested for anti-S1-RBD. We estimated weighted seroprevalence adjusted for assay characteristics.
Results
Of the 28,598 sera from general population, 4585 (16%) had IgG antibodies against N, 6647 (23.2%) against S1-RBD and 7436 (26%) against either. The weighted and assay characteristic adjusted seroprevalence against either of the antibodies was 24.1 (95%CI: 23.0%-25.3%). Among 7385 HCWs, the seroprevalence of anti-S1-RBD IgG antibodies was 25.6% (95% CI: 23.5%-27.8%).
Conclusions
Nearly one in four individuals aged > = 10 years from general population as well as HCWs in India were exposed to SARS-CoV-2 by December 2020.
We have searched for Mycobacterium leprae DNA for 36kDa protein in urine using a M. leprae specific PCR technique. A limited number of 16 patients (of which 11 belonged to lepromatous leprosy and five to tuberculoid leprosy) and eight healthy individuals were included for the present study. The number of urine samples positive by PCR were 36.4% (4/11) in lepromatous patients and 40% (2/5) in tuberculoid patients. None of the samples from healthy individuals was positive. To our knowledge, the results indicate, for the first time, the presence of M. leprae DNA in urine from leprosy patients. Another important finding obtained out of the study is that amongst treated patients 66.6% (4/6) were positive whereas amongst untreated only 20% (2/10) were positive. From the present indicative data it appears that treatment improves the PCR results with urine as a sample. Thus, the approach could prove to be useful for monitoring the treatment response of individual patients and needs to be further evaluated with a large number of patients.
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