High seroprevalence of COVID-19 infection in a large slum in South India; what does it tell us about managing a pandemic and beyond?

People living in urban slums or informal settlements are among the most vulnerable communities, highly susceptible to coronavirus disease 2019 (COVID-19) infection and vulnerable to the consequences of the measures taken to control the spread of the virus. Fear and stigma related to infection, mistrust between officials and the population, the often-asymptomatic nature of the disease is likely to lead to under-reporting. We conducted a cross-sectional study to determine the seroprevalence of COVID-19 infection in a large slum in South India 3 months after the index case and recruited 499 adults (age >18 years). The majority (74.3%) were females and about one-third of the population reported comorbidities. The overall seroprevalence of IgG antibody for COVID-19 was 57.9% (95% CI 53.4-62.3). Age, education, occupation and the presence of reported comorbidities were not associated with seroprevalence (P-value >0.05). Case-to-undetected-infections ratio was 1:195 and infection fatality rate was calculated as 2.94 per 10 000 infections. We estimated seroprevalence of COVID-19 was very high in our study population. The focus in this slum should shift from infection prevention to managing the indirect consequences of the pandemic. We recommend seroprevalence studies in such settings before vaccination to identify the vulnerability of COVID-19 infection to optimise the use of insufficient resources. It is a wake-up call to societies and nations, to dedicate paramount attention to slums into recovery and beyond - to build, restore and maintain health equity for the 'Health and wellbeing of all'.

High susceptibility to varicella among urban and rural pregnant women in South India: a brief report.

Varicella infection during pregnancy has serious and/or difficult implications and in some cases lethal outcome. Though epidemiological studies in developing countries reveal that a significant proportion of patients may remain susceptible during pregnancy, such an estimate of susceptible women is not known in India. We designed this study to study the prevalence and factors associated with susceptibility to varicella among rural and urban pregnant women in South India. We prospectively recruited 430 pregnant women and analysed their serum varicella IgG antibodies as surrogates for protection. We estimated seroprevalence, the validity of self-reported history of chickenpox and factors associated with varicella susceptibility. We found 23 (95% CI 19.1-27.3) of women were susceptible. Nearly a quarter (22.2%) of the susceptible women had a history of exposure to chickenpox anytime in the past or during the current pregnancy. Self-reported history of varicella had a positive predictive value of 82.4%. Negative history of chickenpox (adjusted prevalence ratio (PR) 1.85, 95% CI 1.15-3.0) and receiving antenatal care from a rural secondary hospital (adjusted PR 4.08, 95% CI 2.1-7.65) were significantly associated with susceptibility. We conclude that high varicella susceptibility rates during pregnancy were noted and self-reported history of varicella may not be a reliable surrogate for protection.

A comprehensive review of dengue with a focus on emerging solutions for precision and timely detection.

Dengue is a global health problem, caused by the dengue virus (DENV), which belongs to the Flaviviridae family of viruses. The transmission of DENV occurs through vectors, Ae. aegypti and Ae. Albopictus mosquitoes, to the human host, classifying it as a vector-borne disease. The disease incidence is increasing at an alarming rate and needs to be tackled to reduce the morbidity and mortality caused by the disease. Environmental and clinical surveillance, detection of the virus, and diagnostics are critical tools to address this issue. In this comprehensive review, we explore various diagnostic techniques and the associated challenges within the context of dengue. While we briefly touch upon dengue's epidemiology, serotypes, and pathogenesis, our primary emphasis remains on diagnostics. We delve into the intricacies of these diagnostic methods, considering both the challenges they entail and the potential they hold in terms of accuracy and accessibility. It's important to note that the review does not extensively cover clinical aspects or regional variations of the disease.

Immunogenicity of SARS-CoV-2 vaccines BBV152 (COVAXIN®) and ChAdOx1 nCoV-19 (COVISHIELD™) in seronegative and seropositive individuals in India: a multicentre, nonrandomised observational study.

Background: There are limited global data on head-to-head comparisons of vaccine platforms assessing both humoral and cellular immune responses, stratified by pre-vaccination serostatus. The COVID-19 vaccination drive for the Indian population in the age group 18-45 years began in April 2021 when seropositivity rates in the general population were rising due to the delta wave of COVID-19 pandemic during April-May 2021. Methods: Between June 30, 2021, and Jan 28, 2022, we enrolled 691 participants in the age group 18-45 years across four clinical sites in India. In this non-randomised and laboratory blinded study, participants received either two doses of Covaxin® (4 weeks apart) or two doses of Covishield™ (12 weeks apart) as per the national vaccination policy. The primary outcome was the seroconversion rate and the geometric mean titre (GMT) of antibodies against the SARS-CoV-2 spike and nucleocapsid proteins post two doses. The secondary outcome was the frequency of cellular immune responses pre- and post-vaccination. Findings: When compared to pre-vaccination baseline, both vaccines elicited statistically significant seroconversion and binding antibody levels in both seronegative and seropositive individuals. In the per-protocol cohort, Covishield™ elicited higher antibody responses than Covaxin® as measured by seroconversion rate (98.3% vs 74.4%, p < 0.0001 in seronegative individuals; 91.7% vs 66.9%, p < 0.0001 in seropositive individuals) as well as by anti-spike antibody levels against the ancestral strain (GMT 1272.1 vs 75.4 binding antibody units/ml [BAU/ml], p < 0.0001 in seronegative individuals; 2089.07 vs 585.7 BAU/ml, p < 0.0001 in seropositive individuals). As participants at all clinical sites were not recruited at the same time, site-specific immunogenicity was impacted by the timing of vaccination relative to the delta and omicron waves. Surrogate neutralising antibody responses against variants-of-concern including delta and omicron was higher in Covishield™ recipients than in Covaxin® recipients; and in seropositive than in seronegative individuals after both vaccination and asymptomatic infection (omicron variant). T cell responses are reported from only one of the four site cohorts where the vaccination schedule preceded the omicron wave. In seronegative individuals, Covishield™ elicited both CD4+ and CD8+ spike-specific cytokine-producing T cells whereas Covaxin® elicited mainly CD4+ spike-specific T cells. Neither vaccine showed significant post-vaccination expansion of spike-specific T cells in seropositive individuals. Interpretation: Covishield™ elicited immune responses of higher magnitude and breadth than Covaxin® in both seronegative individuals and seropositive individuals, across cohorts representing the pre-vaccination immune history of most of the vaccinated Indian population. Funding: Corporate social responsibility (CSR) funding from Hindustan Unilever Limited (HUL) and Unilever India Pvt. Ltd. (UIPL).

Antibody titres in fully vaccinated healthcare workers with and without breakthrough infection during the Delta and Omicron waves.

Introduction: Assessment of antibody response to vaccination against SARS CoV2 has clinical, public health, and policy implications during the pandemic and in the context of future waves. Method: In this repeated cross-sectional study, we estimated total binding antibody levels to the spike protein of the SARS CoV2 virus post two doses of Covishield vaccine among 133 health care workers (HCWs) (phase 1), followed by antibody levels among a subset (n = 61) of this group at 9 months after the second dose (phase 2). The time period of the first and second blood collection corresponds to Delta and Omicron waves, respectively. Results: We report 100% seroconversion post 28 days of the second dose of the Covishield vaccine among infection naïve HCWs. In this study, 33% had a breakthrough infection in phase 1 and 24% reported a history of infection in phase 2. The antibody titres were higher in the breakthrough infection group compared to the infection naïve group during both Delta and Omicron waves. Conclusion: This shows that there is a good seroconversion with two doses of vaccine, weaning of antibody with time, and a rise of antibody titre if infected with SARS CoV 2 subsequently.

Validating saliva as a biological sample for cost-effective, rapid and routine screening for SARS-CoV-2.

PURPOSE: Compared to nasopharyngeal/oropharyngeal swabs (N/OPS-VTM), non-invasive saliva samples have enormous potential for scalability and routine population screening of SARS-CoV-2. In this study, we investigate the efficacy of saliva samples relative to N/OPS-VTM for use as a direct source for RT-PCR based SARS-CoV-2 detection. METHODS: We collected paired nasopharyngeal/oropharyngeal swabs and saliva samples from suspected positive SARS-CoV-2 patients and tested using RT-PCR. We used generalized linear models to investigate factors that explain result agreement. Further, we used simulations to evaluate the effectiveness of saliva-based screening in restricting the spread of infection in a large campus such as an educational institution. RESULTS: We observed a 75.4% agreement between saliva and N/OPS-VTM, that increased drastically to 83% in samples stored for less than three days. Such samples processed within two days of collection showed 74.5% test sensitivity. Our simulations suggest that a test with 75% sensitivity, but high daily capacity can be very effective in limiting the size of infection clusters in a workspace. Guided by these results, we successfully implemented a saliva-based screening in the Bangalore Life Sciences Cluster (BLiSC) campus. CONCLUSION: These results suggest that saliva may be a viable alternate source for SARS-CoV-2 surveillance if samples are processed immediately. Although saliva shows slightly lower sensitivity levels when compared to N/OPS-VTM, saliva collection is logistically advantageous. We strongly recommend the implementation of saliva-based screening strategies for large workplaces and in schools, as well as for population-level screening and routine surveillance as we learn to live with the SARS-CoV-2 virus.

Isoniazid resistance in patients with Extrapulmonary Tuberculosis using line probe assay in a private multispecialty hospital in Bangalore, India.

We aimed to study the rate of isoniazid (INH) resistance in Extrapulmonary Tuberculosis samples from a private care setting. A Line probe assay was performed on 74 culture isolates of Mycobacterium tuberculosis or directly on extrapulmonary samples received in our laboratory from 2018 to 2021. The INH mono-resistance among these extrapulmonary samples was 6.7%. (5 among 74) (95% CI: 1.04%-12.48%) Resistance to rifampicin was not detected. Increasing the availability and leveraging public private partnerships in hospitals for universal testing for INH resistance may increase detection of INH monoresistance in EP-TB and improve the strategy for TB elimination.

Preservation of Streptococcus pneumoniae quality control strains using chocolate agar blocks in glycerol at minus 70 degrees celsius.

We present a method for storage of the quality control strain of S. pneumoniae that could be used in low resource settings. Small blocks of chocolate agar with growth were placed in glycerol (60%V/V) and stored at minus 70 °C. Viability and cultural characteristics were maintained for the testing period of 10 months. The wide availability of both chocolate agar and glycerol make this a suitable alternative to other specialized formulations usually used to maintain stocks of S. pneumoniae ATCC 49619 strain required for quality control of susceptibility testing.

Are hospitals epicentres of COVID19 transmission? Findings of serial serosurveys among healthcare workers from a tertiary hospital in South India.

We conducted a serial cross-sectional study and used blood bank donors serosurvey and the ICMR serosurvey reports for comparison. Seroprevalence was 0% among HCWs (n-211) and blood bank donors (n-210) during the first phase while ICMR serosurvey reported 0.5% among general population in the district at the same time. In phase 2, we estimated a seroprevalence of 9.2% as compared to 18.8% among general population. Seroprevalence among HCWs was comparable to that of the general population during both phases. We postulate that good infection control policies and practice can provide safe working environment without additional risk to HCWs.

Seroprevalence of SARS CoV-2 among children after the second surge (June 2021) in a rural district of South India: Findings and lessons from a population-based survey.

Objective: To determine the seroprevalence of SARS COV 2 among children in the Bangalore Rural district. Methods: We conducted a cross-sectional study after the second surge of COVID-19 from 14 June to 13 July 2021 and recruited 412 children through house to house visits from four villages in a rural district. We administered a questionnaire to collect demographics and details of COVID-19 infection and used the ABCHEK Antibody Card test (NuLifecare,India) which is an ICMR approved test for detecting antibodies (IgG & IgM) by immunochromatography using the finger prick method. We used Statistical Package for the Social Sciences version 20.0 for analysis. Results: Our participants had an age group ranging from 11 months to 18 years. There was an almost equal distribution of boys (48.3%) and girls (51.7%). We estimated seroprevalence of 45.9% (95% CI: 41-50.8) among children. Seroprevalence was significantly associated with a history of symptoms suggestive of COVID-19 in the past, the seropositive status of the parents, and any other family members being tested positive. Age and gender of the child, education and occupation of the parents were not associated with the seropositivity status of the child. Conclusion: Seroprevalence of COVID-19 among children corresponds to adult seroprevalence during the same time interval. This knowledge can be of practical application where adult prevalence is documented. Unvaccinated children in low-resource settings need special attention with respect to monitoring for new mutations as well as managing endemic needs.

Seroprevalence of COVID-19 infection among vaccine naïve population after the second surge (June 2020) in a rural district of South India: A community-based cross-sectional study.

OBJECTIVE: To determine the seroprevalence of the SARS Cov 2 infection among vaccine naive population in a rural district of South India post-second surge. METHODOLOGY: We conducted a cross-sectional study in the five villages of a randomly chosen sub-district in the Bangalore rural district. We did house to house surveys and recruited 831 vaccine naive adults in July 2021. We tested samples for the presence of antibodies (including IgG & IgM) to SARS CoV-2 using the Roche Elecsys SARS-CoV-2 -S assay that quantifies antibodies against the receptor-binding domain (RBD) of the spike (S) protein. RESULTS: We estimated an overall prevalence of 62.7% (95% CI: 59.3-66.0) and an age-and gender-adjusted seroprevalence of 44.9% (95% CI: 42.5-47.4). When adjusted for test performance, the seroprevalence was 74.64% (95% CI: 70.66-78.47). The case-to-undetected-infected ratio (CIR) was 1: 8.65 (95% CI 1:8.1-1:9.1), and the Infection Fatality Rate (IFR) was 16.27 per 100,00 infections as of 13 July 2021. A history of at least one symptom suggestive of COVID-19 or a positive COVID-19 test of self or a family member in the past were significantly associated with seropositivity. CONCLUSION: We report a high seroprevalence of COVID-19 infection despite the advantages of low population density and well-ventilated landscapes in rural areas. CIR and IFR were higher than the previous serosurvey conducted in the same population during the first surge. The thought of achieving herd immunity comes with relief. However, it's vital to put efforts into building population health and rural health infrastructure to avert future health catastrophes.

COVID-19 symptoms are reduced by targeted hydration of the nose, larynx and trachea.

Dehydration of the upper airways increases risks of respiratory diseases from COVID-19 to asthma and COPD. We find in human volunteer studies involving 464 human subjects in Germany, the US, and India that respiratory droplet generation increases by up to 4 orders of magnitude in dehydration-associated states of advanced age (n = 357), elevated BMI-age (n = 148), strenuous exercise (n = 20) and SARS-CoV-2 infection (n = 87), and falls with hydration of the nose, larynx and trachea by calcium-rich hypertonic salts. We also find in a protocol of exercise-induced airway dehydration that hydration of the airways by calcium-rich salts increases oxygenation relative to a non-treatment control (P < 0.05). In a random control study of COVID-19 positive subjects (n = 40), thrice-a-day delivery of the calcium-rich hypertonic salts (active) suppressed respiratory droplet generation by 51% ± 11% and increased oxygen saturation over three days of treatment by 48.08% ± 9.61% (P < 0.001), while no changes were observed in the nasal-saline control group. Self-reported symptoms significantly declined in the active group and did not decline in the control group. Hydration of the upper airways appears promising as a non-drug approach for reducing risks of respiratory diseases such as COVID-19.

Seroprevalence of COVID-19 infection in a rural district of South India: A population-based seroepidemiological study.

OBJECTIVES: We aimed to estimate the seroprevalence of COVID-19 in a rural district of South India, six months after the index case. METHODOLOGY: We conducted a cross-sectional study of 509 adults aged more than 18 years. From all the four subdistricts, two grampanchayats (administrative cluster of 5-8 villages) were randomly selected followed by one village through convenience. The participants were invited for the study to the community-based study kiosk set up in all the eight villages through village health committees. We collected socio-demographic characteristics and symptoms using a mobile application-based questionnaire, and we tested samples for the presence of IgG antibodies for SARS CoV-2 using an electro chemiluminescent immunoassay. We calculated age-gender adjusted and test performance adjusted seroprevalence. RESULTS: The age-and gender-adjusted seroprevalence was 8.5% (95% CI 6.9%- 10.8%). The unadjusted seroprevalence among participants with hypertension and diabetes was 16.3% (95% CI:9.2-25.8) and 10.7% (95% CI: 5.5-18.3) respectively. When we adjusted for the test performance, the seroprevalence was 6.1% (95% CI 4.02-8.17). The study estimated 7 (95% CI 1:4.5-1:9) undetected infected individuals for every RT-PCR confirmed case. Infection Fatality Rate (IFR) was calculated as 12.38 per 10000 infections as on 22 October 2020. History of self-reported symptoms and education were significantly associated with positive status (p < 0.05). CONCLUSION: A significant proportion of the rural population in a district of south India remains susceptible to COVID-19. A higher proportion of susceptible, relatively higher IFR and a poor tertiary healthcare network stress the importance of sustaining the public health measures and promoting early access to the vaccine are crucial to preserving the health of this population. Low population density, good housing, adequate ventilation, limited urbanisation combined with public, private and local health leadership are critical components of curbing future respiratory pandemics.