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.

Clinical profile of patients infected with suspected SARS-CoV-2 Omicron variant of concern, Tamil Nadu, India, December 2021-January 2022.

Background & objectives: COVID-19 cases have been rising rapidly in countries where the SARS-CoV-2 variant of concern (VOC), Omicron (B.1.1.529) has been reported. We conducted a study to describe the epidemiological and clinical characteristics and outcomes of COVID-19 patients with 'S' gene target failure (SGTF, suspected Omicron). Furthermore, their clinical outcomes with COVID-19 patients with non-SGTF (non-Omicron) were also compared. Methods: This study was conducted in Tamil Nadu, India, between December 14, 2021 and January 7, 2022 among patients who underwent reverse transcription-PCR testing for SARS-CoV-2 in four laboratories with facilities for S gene screening. Consecutively selected COVID-19 patients with SGTF were telephonically contacted, seven and 14 days respectively after their date of positive result to collect information on the socio-demographic characteristics, previous history of COVID-19, vaccination status and clinical course of illness along with treatment details. To compare their outcomes with non-SGTF patients, one randomly suspected non-Omicron case for every two suspected Omicron cases from the line-list were selected, matching for the date of sample collection and the testing laboratory. Results: A total of 1175 SGTF COVID-19 patients were enrolled for this study. Almost 6 per cent (n=72) reported a history of previous infection. 141 (13.5%) suspected Omicron cases were non-vaccinated, while 148 (14.2%) and 703 (67.4%) had received valid one and two doses of COVID-19 vaccines, respectively. Predominant symptoms reported included fever (n=508, 43.2%), body pain (n=275, 23.4%), running nose (n=261, 22.2%) and cough (n=249, 21.2%). Five (0.4%) of the 1175 suspected Omicron cases required oxygen supplementation as compared to ten (1.6%) of the 634 suspected non-Omicron cases. No deaths were reported among omicron suspects, whereas there were four deaths among suspected non-Omicron cases. Interpretation & conclusions: Majority of the suspected Omicron cases had a mild course of illness. The overall severity of these cases was less compared to the suspected non-Omicron cases.

Preparedness for reopening and conduct of schools during and post COVID-19 period

COVID-19 has thrown the educational system of India into turmoil. India with its vast and diverse educational scenario has to prepare itself for reopening and conducting schools, taking into account the disparity in the economic strata among its institutions. Schools serve as nodal centres for distribution of nutritious food, for physical fitness and also take care of psychosocial well-being of the children. Hence, closure of schools causes multidimensional effects. Lack of space, resource constraints, disparity in accessing technological advancements are huge challenges in implementing uniform policies while reopening. The introduction of new online and offline platforms of education by the efforts of government has paved the way for a new learning methodology. This combined with additional efforts to take care of the nutritional and physical needs of the children will usher in a different era in Indian educational system. This article discusses policies that can be implemented by schools with the support and willingness of all stake holders from the students to the society at large. The methods and need to implement principles of social distancing, respiratory hygiene and etiquette, minimising large gatherings, restructuring of seating arrangements, self-discipline in reporting and treatment of illnesses are discussed.

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.