Contribution of infection and vaccination to population-level seroprevalence through two COVID waves in Tamil Nadu, India (preprint)

Four rounds of serological surveys were conducted, spanning two COVID waves (October 2020 and April-May 2021), in Tamil Nadu (population 72 million) state in India. Each round included representative populations in each district of the state, totaling  ≥20,000 persons per round. State-level seroprevalence was 31.5% in round 1 (October-November 2020), after India’s first COVID wave. Seroprevalence fell to 22.9% in 2 (April 2021), consistent with waning of SARS-Cov-2 antibodies from natural infection. Seroprevalence rose to 67.1% by round 3 (June-July 2021), reflecting infections from the Delta-variant induced second COVID wave. Seroprevalence rose to 93.1% by round 4 (December 2021-January 2022), reflecting higher vaccination rates. Antibodies also appear to wane after vaccination. Seroprevalence in urban areas was higher than in rural areas, but the gap shrunk over time (35.7 v. 25.7% in round 1, 89.8% v. 91.4% in round 4) as the epidemic spread even in low-density rural areas. The study documents substantial waning of SARS-CoV-2 antibodies at the population level and demonstrates how to calculate the extent to which infection and vaccination separately contribute to seroprevalence estimates.

Household catastrophic health expenditure for COVID-19 during March-August 2021, in South India: a cross-sectional study.

BACKGROUND: The Coronavirus disease 2019 (COVID-19) pandemic increased the utilisation of healthcare services. Such utilization could lead to higher out-of-pocket expenditure (OOPE) and catastrophic health expenditures (CHE). We estimated OOPE and the proportion of households that experienced CHE by conducting a cross-sectional survey of 1200 randomly selected confirmed COVID-19 cases. METHODS: A cross-sectional survey was conducted by telephonic interviews of 1200 randomly selected COVID-19 patients who tested positive between 1 March and 31 August 2021. We collected household-level information on demographics, income, expenditure, insurance coverage, direct medical and non-medical costs incurred toward COVID-19 management. We estimated the proportion of CHE with a 95% confidence interval. We examined the association of household characteristics; COVID-19 cases, severity, and hospitalisation status with CHE. A multivariable logistic regression analysis was conducted to ascertain the effects of variables of interest on the likelihood that households face CHE due to COVID-19. RESULTS: The mean (95%CI) OOPE per household was INR 122,221 (92,744-1,51,698) [US$1,643 (1,247-2,040)]. Among households, 61.7% faced OOPE, and 25.8% experienced CHE due to COVID-19. The odds of facing CHE were high among the households; with a family member over 65 years [OR = 2.89 (2.03-4.12)], with a comorbid individual [OR = 3.38 (2.41-4.75)], in the lowest income quintile [OR = 1.82 (1.12-2.95)], any member visited private hospital [OR = 11.85 (7.68-18.27)]. The odds of having CHE in a household who have received insurance claims [OR = 5.8 (2.81- 11.97)] were high. Households with one and more than one severe COVID-19 increased the risk of CHE by more than two-times and three-times respectively [AOR = 2.67 (1.27-5.58); AOR = 3.18 (1.49-6.81)]. CONCLUSION: COVID-19 severity increases household OOPE and CHE. Strengthening the public healthcare and health insurance with higher health financing is indispensable for financial risk protection of households with severe COVID-19 from CHE.

Household Catastrophic Health Expenditure for COVID-19 during March-August 2021, in South India: A Cross-Sectional Study (preprint)

Background The Coronavirus disease 2019 (COVID-19) pandemic increased the utilisation of healthcare services. Such utilization could lead to higher out-of-pocket expenditure (OOPE) and catastrophic health expenditures (CHE). We estimated OOPE and the proportion of households that experienced CHE by conducting a cross-sectional survey of 1200 randomly selected COVID-19.Methods A cross-sectional survey was conducted by telephonic interviews of 1200 randomly selected COVID-19 patients who tested positive between 1 March and 31 August 2021. We collected household-level information on demographics, income, expenditure, insurance coverage, direct medical and non-medical costs incurred toward COVID-19 management. We estimated the proportion of CHE with a 95% Confidence interval. Multivariate logistic regression was used to examine the association between the number of severe COVID-19 and CHE.Results The mean OOPE per household was INR 122,221 (92,744 to 51,698) [US$1,643 (1,247 to 2,040)]. Among households, 61.7% faced OOPE, and 25.8% experienced CHE due to COVID-19. The odds of facing CHE were high among the households; with a family member over 65 years [OR = 2.89 (2.03 to 4.12)], with a comorbid individual [OR = 3.38 (2.41 to 4.75)], in the lowest income quintile [OR = 1.82 (1.12 to 2.95)], any member visited private hospital [OR = 11.85 (7.68 to 18.27)]. The odds of having CHE in a household who have received insurance claims [OR = 5.8 (2.81 to 11.97)] were high. Households having one severe COVID-19 and more than one increased the risk of CHE by four-times [AOR = 4.33 (2.13–8.34)] and five-times [AOR = 5.10 (2.42–10.74)] respectively.Conclusion COVID-19 severity increases household OOPE and CHE. Strengthening the public healthcare and health insurance with higher health financing is indispensable for financial risk protection of households with severe COVID-19 from CHE.

Role of Covid vaccine in determining ICU admission and death due to Covid -19 in Tamil Nadu (preprint)

COVID 19 pandemic threatened the world in terms of its rapid spread, strain on health infrastructure and many people lost their lives due to COVID. Mass Vaccination of public against Covid-19 were done with the notion that it protects against the severe form of the disease and death due to Covid 19. Covid vaccination was rolled out in Tamil Nadu from 16th January 2021 in a phased manner. This study was done using secondary data to assess the role of COVID vaccination in preventing ICU admission and death due to Covid 19 in Tamil Nadu for the period of August to December 2021. Unvaccinated individuals contributed to a higher proportion of hospitalization (60.9%) and ICU admission (65.5%) among Covid-19 infected during this period. Similarly, among patients who died due to Covid-19, 75.5% were unvaccinated. Odds of ICU admission and death among unvaccinated was 2.01 and 3.19 -times higher compared to fully vaccinated individuals infected with Covid-19. Unvaccinated Covid-19 patients had 2.73 and 1.46 times increased odds of dying and ICU admission respectively, compared to partially vaccinated. Population Attributable Risk showed that receiving at least one dose of vaccine could have reduced the mortality among Covid patients by 54% and ICU admission by 23.3%. This article emphasizes the need for vaccination against Covid-19 to reduce ICU admission and death among those infected with Covid 19.

S Gene Target Failure (SGTF) in Commercial Multiplex RT-PCR assay as indicator to detect SARS-CoV-2 VOC B.1.1.7 lineage in Tamil Nadu, India (preprint)

Emergence of Severe Acute Respiratory Syndrome Corona Virus-2 (SARS-CoV-2) Variants of Concern (VOC) possessing improved virulence, transmissibility and/or immune-escape capabilities has raised significant public health concerns. In order to identify VOCs, WHO recommends Whole-Genome Sequencing approach, which is costly and involves longer completion time. Hence, potential role of commercial multiplex RT-PCR kit to screen variants rapidly is being attempted in this study. A total of 1200 suspected COVID samples from different districts of Tamil Nadu State (India) were screened with Thermo TaqPath RT-PCR kit and Altona Realstar RT-PCR Assay kit. Among 1200 screened, S-gene target failure (SGTF) phenomenon were identified in 112 samples while testing with TaqPath RT-PCR Kit. 100% concordant results were observed between SGTF phenomenon and whole-genome sequencing (WGS) results in detecting SARS-CoV-2 VOC B.1.1.7. TaqPath RT-PCR assay testing can be utilized by laboratories to screen rapidly the VOC B.1.1.7 variants, thus enabling early detection of B.1.1.7 variant infection and transmission in population. This in turn will pave way to implement suitable preventive measures by appropriate authorities to control the transmission of the viral variant.

Seroprevalence in Tamil Nadu through India's two COVID waves: Evidence on antibody decline following infection and vaccination (preprint)

Three rounds of population-representative serological studies through India's two COVID waves (round 1, 19 October-30 November 2020; round 2, 7-30 April 2021; and round 3, 28 June-7 July, 2021) were conducted at the district-level in Tamil Nadu state (population 72 million). State-level seroprevalence in rounds 1, 2 and 3 were 31.5%, 22.9%, and 67.1%. Estimated seroprevalence implies that at least 22.6 and 48.1 million persons were infected by the 30 November 2020 and 7 July 2021. There was substantial variation across districts in the state in each round. Seroprevalence ranged from 11.1 to 49.8% (round 1), 7.9 to 50.3% (round 2), and 37.8 to 84% (round 3). Seroprevalence in urban areas was higher than in rural areas (35.7 v. 25.7% in round 1, 74.8% v. 64.1% in round 3). Females had similar seroprevalence to males (30.8 v. 30.2% in round 1, 67.5 v. 65.5% in round 3). While working age populations (age 40-49: 31.6%) had significantly higher seroprevalence than the youth (age 18-29: 30.4%) or elderly (age 70+: 26.5%) in round 1, only the gap between working age (age 40-49: 66.7%) and elderly (age 70+: 59.6%) remained significant in round 3. Seroprevalence was greater among those who were vaccinated for COVID (25.7% v. 20.9% in round 2, 80.0% v. 62.3% in round 3). While the decline in seroprevalence from rounds 1 to 2 suggests antibody decline after natural infection, we do not find a significant decline in antibodies among those receiving at least 1 dose of COVID vaccine between rounds 2 and 3.