High prevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibodies among unvaccinated children of Chandigarh, Northwest India, in a household-based paediatric serosurvey post-second wave of pandemic (June to July 2021).

Current national severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination policy covers children aged >12 years. Unvaccinated, uninfected children remain susceptible to SARS-CoV-2 and play a role in community transmission, as paediatric infection is mostly mild or asymptomatic. To estimate the proportion of susceptible children in a community for public health measures, there is a need to assess the extent of natural infection. We performed a cross-sectional household serosurvey of SARS-CoV-2 antibodies in unvaccinated children aged between 6 and 18 years after the second COVID-19 wave. Anti-SARS-CoV-2 immunoglobin G (IgG) testing in serum was done using chemiluminescence immunoassay. We used a logistic regression model to investigate predicted factors of seropositivity. We observed a high prevalence (weighted average: 68.3%) of anti-SARS-CoV-2 IgG in 2700 enrolled children. Logistic regression for predictors of IgG seropositivity showed lower odds in households with completely vaccinated adults (adjusted odds ratio [OR]: 0.43, 95% confidence interval [CI]: 0.26-0.71, P = 0.0011) compared with households with unvaccinated adults. Other factors for low seropositivity included frontline workers as family members (adjusted OR: 0.69, 95% CI: 0.52-0.91, P = 0.0091) and non-crowded households (adjusted OR: 0.74, 95% CI: 0.61-0.89, P = 0.0019). A high SARS-CoV-2 IgG prevalence in unvaccinated children was indicative of previous exposure to potentially infected contacts. This implies in-person academic activities for children can be continued during future community transmission. Comparatively lower seropositivity in children of completely vaccinated households or frontline workers suggests decreased transmission due to vaccination-induced immunity of family members. Vaccination will still be required in these children to maintain protective IgG levels, particularly in low seroprevalence groups.

Ghosh A ，Goyal K ，Singh R ，Lakshmi PVM ，Kaur R ，Kumar V ，Muralidharan J ，Puri GD ，Ram J ，Singh MP ... -  《-》

Seroprevalence of IgG antibodies against SARS-CoV-2 among the general population and healthcare workers in India, June-July 2021: A population-based cross-sectional study.

Murhekar MV ，Bhatnagar T ，Thangaraj JWV ，Saravanakumar V ，Santhosh Kumar M ，Selvaraju S ，Rade K ，Kumar CPG ，Sabarinathan R ，Asthana S ，Balachandar R ，Bangar SD ，Bansal AK ，Bhat J ，Chakraborty D ，Chopra V ，Das D ，Devi KR ，Dwivedi GR ，Jain A ，Khan SMS ，Kumar MS ，Laxmaiah A ，Madhukar M ，Mahapatra A ，Ramesh T ，Rangaraju C ，Turuk J ，Yadav S ，Bhargava B ，ICMR serosurveillance group ... -  《-》

Seroprevalence of SARS-CoV-2-specific anti-spike IgM, IgG, and anti-nucleocapsid IgG antibodies during the second wave of the pandemic: A population-based cross-sectional survey across Kashmir, India.

Within Kashmir, which is one of the topographically distinct areas in the Himalayan belt of India, a total of 2,236 cumulative deaths occurred by the end of the second wave. We aimed to conduct this population-based study in the age group of 7 years and above to estimate the seropositivity and its attributes in Kashmir valley. We conducted a community-based household-level cross-sectional study, with a multistage, population-stratified, probability-proportionate-to-size, cluster sampling method to select 400 participants from each of the 10 districts of Kashmir. We also selected a quota of healthcare workers, police personnel, and antenatal women from each of the districts. Households were selected from each cluster and all family members with age 7 years or more were invited to participate. Information was collected through a standardized questionnaire and entered into Epicollect 5 software. Trained healthcare personnel were assigned for collecting venous blood samples from each of the participants which were transferred and processed for immunological testing. Testing was done for the presence of SARS-CoV-2-specific anti-spike IgM, IgG antibodies, and anti-nucleocapsid IgG antibodies. Weighted seropositivity was estimated along with the adjustment done for the sensitivity and specificity of the test used. The data were collected from a total of 4,229 participants from the general population within the 10 districts of Kashmir. Our results showed that 84.84% (95% CI 84.51-85.18%) of the participants were seropositive in the weighted imputed data among the general population. In multiple logistic regression, the variables significantly affecting the seroprevalence were the age group 45-59 years (odds ratio of 0.73; 95% CI 0.67-0.78), self-reported history of comorbidity (odds ratio of 1.47; 95% CI 1.33-1.61), and positive vaccination history (odds ratio of 0.85; 95% CI 0.79-0.90) for anti-nucleocapsid IgG antibodies. The entire assessed variables showed a significant role during multiple logistic regression analysis for affecting IgM anti-spike antibodies with an odds ratio of 1.45 (95% CI 1.32-1.57) for age more than 60 years, 1.21 (95% CI 1.15-1.27) for the female gender, 0.87 (95% CI 0.82-0.92) for urban residents, 0.86 (95% CI 0.76-0.92) for self-reported comorbidity, and an odds ratio of 1.16 (95% CI 1.08-1.24) for a positive history of vaccination. The estimated infection fatality ratio was 0.033% (95% CI: 0.034-0.032%) between 22 May and 31 July 2021 against the seropositivity for IgM antibodies. During the second wave of the SARS-CoV-2 pandemic, 84.84% (95% CI 84.51-85.18%) of participants from this population-based cross-sectional sample were seropositive against SARS-CoV-2. Despite a comparatively lower number of cases reported and lower vaccination coverage in the region, our study found such high seropositivity across all age groups, which indicates the higher number of subclinical and less severe unnoticed caseload in the community.

Lone KS ，Khan SMS ，Qurieshi MA ，Majid S ，Pandit MI ，Haq I ，Ahmad J ，Bhat AA ，Bashir K ，Bilquees S ，Fazili AB ，Hassan M ，Jan Y ，Kaul RR ，Khan ZA ，Mushtaq B ，Nazir F ，Qureshi UA ，Raja MW ，Rasool M ，Asma A ，Bhat AA ，Chowdri IN ，Ismail S ，Jeelani A ，Kawoosa MF ，Khan MA ，Khan MS ，Kousar R ，Lone AA ，Nabi S ，Qazi TB ，Rather RH ，Sabah I ，Sumji IA ... -  《Frontiers in Public Health》

SARS-CoV-2 antibody seroprevalence in India, August-September, 2020: findings from the second nationwide household serosurvey.

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. We 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 laboratory-confirmed 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. 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. 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. Indian Council of Medical Research.

Murhekar MV ，Bhatnagar T ，Selvaraju S ，Saravanakumar V ，Thangaraj JWV ，Shah N ，Kumar MS ，Rade K ，Sabarinathan R ，Asthana S ，Balachandar R ，Bangar SD ，Bansal AK ，Bhat J ，Chopra V ，Das D ，Deb AK ，Devi KR ，Dwivedi GR ，Khan SMS ，Kumar CPG ，Kumar MS ，Laxmaiah A ，Madhukar M ，Mahapatra A ，Mohanty SS ，Rangaraju C ，Turuk A ，Baradwaj DK ，Chahal AS ，Debnath F ，Haq I ，Kalliath A ，Kanungo S ，Kshatri JS ，Lakshmi GGJN ，Mitra A ，Nirmala AR ，Prasad GV ，Qurieshi MA ，Sahay S ，Sangwan RK ，Sekar K ，Shukla VK ，Singh PK ，Singh P ，Singh R ，Varma DS ，Viramgami A ，Panda S ，Reddy DCS ，Bhargava B ，ICMR Serosurveillance Group ... -  《Lancet Global Health》

Prevalence of SARS-CoV-2 infection in India: Findings from the national serosurvey, May-June 2020.

Murhekar MV ，Bhatnagar T ，Selvaraju S ，Rade K ，Saravanakumar V ，Vivian Thangaraj JW ，Kumar MS ，Shah N ，Sabarinathan R ，Turuk A ，Anand PK ，Asthana S ，Balachandar R ，Bangar SD ，Bansal AK ，Bhat J ，Chakraborty D ，Rangaraju C ，Chopra V ，Das D ，Deb AK ，Devi KR ，Dwivedi GR ，Salim Khan SM ，Haq I ，Kumar MS ，Laxmaiah A ，Madhuka ，Mahapatra A ，Mitra A ，Nirmala AR ，Pagdhune A ，Qurieshi MA ，Ramarao T ，Sahay S ，Sharma YK ，Shrinivasa MB ，Shukla VK ，Singh PK ，Viramgami A ，Wilson VC ，Yadav R ，Girish Kumar CP ，Luke HE ，Ranganathan UD ，Babu S ，Sekar K ，Yadav PD ，Sapkal GN ，Das A ，Das P ，Dutta S ，Hemalatha R ，Kumar A ，Narain K ，Narasimhaiah S ，Panda S ，Pati S ，Patil S ，Sarkar K ，Singh S ，Kant R ，Tripathy S ，Toteja GS ，Babu GR ，Kant S ，Muliyil JP ，Pandey RM ，Sarkar S ，Singh SK ，Zodpey S ，Gangakhedkar RR ，S Reddy DC ，Bhargava B ... -  《-》