Anti SARS-CoV-2 Antibody Kinetics up to 6 months of follow-up: Result from a Nation-wide Population-based, Age Stratified Sero-Epidemiological Prospective Cohort Study in India (preprint)

Repeated serological testing tells about the change in the overall infection in a community. This study aimed to evaluate changes in antibody prevalence and kinetics in a closed cohort over six months in different sub-populations in India. The study included 10,000 participants from rural and urban areas in five states and measured SARS-CoV-2 antibodies in serum in three follow-up rounds. The overall seroprevalence increased from 73.9% in round one to 90.7% in round two and 92.9% in round three. Among seropositive rural participants in round one, 98.2% remained positive in round two, and this percentage remained stable in urban and tribal areas in round three. The results showed high antibody prevalence that increased over time and was not different based on area, age group, or sex. Vaccinated individuals had higher antibody prevalence, and nearly all participants had antibody positivity for up to six months.

Hospital based contact tracing of COVID-19 patients and health care workers and risk stratification of exposed health care workers during the COVID-19 Pandemic in Eastern India (preprint)

Introduction: Contact tracing and subsequently quarantining of HCWs is essential to minimize further transmission. In this study, we have reported our experience of contact tracing and risk categorization in a tertiary care teaching hospital in Eastern India. Methodology: This is a secondary data analysis of routine data collected from 19th March to 31st August 2020 during the process of contact tracing in a tertiary care teaching hospital in India amongst 3411 health care workers (HCWs). HCWs exposed to COVID-19 infections were categorized as per the risk stratification guidelines and the high risk cases were quarantined for 14 days and tested on 7th day of last contact. The low risk contacts were encouraged to closely monitor their symptoms and allowed to continue work. Results: Out of 3411 contacts 890 (26.1%) were high risk contacts and 2521 (73.9%) were low risk contacts. The test positivity rate of high risk contact was 3.82% and for low risk contact was 1.9%. Number of high risk contacts was more in Non-COVID area (15.84) as compared to COVID area (0.27); p value < 0.001), amongst IPD patients (6.61) as compared to staff (4.02) and OPD (0.22) ; p value = 0.009 and when clustering of cases present (14.35) as compared to isolated cases (8.21); p value < 0.001 Conclusion: The case identification, risk stratification and contact tracing have helped in reducing the number of contacts with due course of time, so preventing the depletion of human resources for continuing health care. The contact tracing approach designed in the current study can also be implemented in other healthcare settings. Key word: COVID-19, contact tracing, health care workers, risk stratification

The COVID-19 Spread in India and Its Dependence on Temperature and Relative Humidity (preprint)

The coronavirus disease 2019 (COVID-19), the pandemic is an unprecedented health emergency never seen in the recorded history of humankind due to its sheer scale, rapid spread, and subsequent shock to the global economy. The past respiratory viral pandemics of the 21st century (SARS-CoV-2 in 2003, Influenza AH1N1 in 2009) have revealed seasonality in environmental factors to play a role in the dynamics of their spread. Here, we report the observed state-level relationship between environmental factors such as temperature (T), relative humidity (RH), specific humidity (SH), and solar radiation (SR) on the COVID-19 spread over the Indian region. The results show that T and RH have a significant impact on the disease growth rate and doubling time. Every degree rise in temperature corresponds to a 0.99 % decrease in the number of cases and an increase in doubling time by ~ 1.13 days implying a slowing down of spread. A similar analysis for RH reveals that more moisture leads to a higher growth rate and reduced doubling time. Lower SH and higher surface-reaching SR are found to reduce the spread and increase the doubling time similar to that of temperature. The range of average state-level T (RH) encountered during this period was between 24 and 35oC (30 and 87%) which implies that environmental impact is still effective at all these T (RH) and is not limited to specific T (RH) ranges. The progression of the season towards monsoon, post-monsoon, and thereafter winter with a continuous reduction in temperature will prove a major challenge for health workers and policymakers attempting to enforce mitigation and control measures.