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Detailed characterisation of immune responses induced by COVID-19 vaccines rolled out in India: COVISHIELDTM (CS) and COVAXIN® (CO) in a pre-exposed population is only recently being discovered. We addressed this issue in subjects who received their primary series of vaccination between November 2021 and January 2022. Both vaccines are capable of strongly boosting Wuhan Spike-specific neutralising antibody, polyfunctional Th1 cytokine producing CD4+ T-cells and single IFN-γ + CD8+ T-cells. Consistent with inherent differences in vaccine platform, the vector-based CS vaccine-induced immunity was of greater magnitude, breadth, targeting Delta and Omicron variants compared to the whole-virion inactivated vaccine CO, with CS vaccinees showing persistent CD8+ T-cells responses until 3 months post primary vaccination. This study provides detailed evidence on the magnitude and quality of CS and CO vaccine induced responses in subjects with pre-existing SARS-CoV-2 immunity in India, thereby mitigating vaccine hesitancy arguments in such a population, which remains a global health challenge. [ABSTRACT FROM AUTHOR]

India has witnessed a high number of COVID-19 cases, but mortality has been quite low, and most cases have been asymptomatic or mild. In early April, we had hypothesized a low COVID-19 mortality in India, based on the concept of cross-immunity. The presence of cross-immunity is presumed to lead to a milder course of disease and allow the time necessary for the development of adaptive immunity by the body to eliminate the virus. Evidence supporting our hypothesis has started showing up. Multiple studies have shown the generation of different T cell subsets and B cells responding to epitopes of viral proteins, especially of the spike protein, as a part of adaptive immunity against SARS-CoV-2. Cross-reactive T-cells have been demonstrated in patients who have been previously exposed to endemic coronaviruses. The interplay of cross-immunity and herd immunity is apparent in the COVID-19 scenario in India from the presence of a large number of asymptomatic or mild cases, a low infection-fatality ratio and a generally flat curve of percentage positivity of cases with respect to total testing, both in periods of strict lock-down and step-wise unlocking. It seems that cross-immunity resulted in faster generation of herd immunity. Although the initial restrictive measures such as lockdown prevented the rapid spread of the outbreak, further extension of such measures and overly expensive ones such as enhanced testing in India will result in a huge burden on the health economics as well as the society. Hence, we propose a restructuring of the health services and approach to COVID-19. The restructured health services should move away from indiscriminate testing, isolation and quarantine, and instead, the emphasis should be on improving facilities for testing and management of only critical COVID cases and the replacement of complete lockdowns by the selective isolation and quarantine of susceptible persons such as the aged and those with co-morbidities. In the process of describing India-specific plans, we emphasize why the development of country-specific plans for tackling epidemics is important, instead of adopting a "one policy fits all" approach. [ABSTRACT FROM AUTHOR]

Purpose: To characterize the presenting features of cytomegalovirus (CMV) retinitis in HIV-positive patients in a developing country in the HAART era.Methods: Retrospective chart review of all patients with CMV retinitis seen at a tertiary-care referral center between January 2006 to June 2017. Demographic and clinical data were collected to study the presenting features and risk factors for blindness.Results: Fifty-five patients with treatment-naïve CMV retinitis were enrolled; 75% were males. CD4 counts were below 50 cells/µL in 51.1%. Bilateral presentation was seen in 61.5%. Half (50.6%) of the eyes were blind at first examination. Zone 1 involvement was present in 46% of the eyes. Retinal area involvement > 25% was the only factor associated significantly with higher incidence of blindness (p = 0.016).Conclusions: There was extensive and bilateral presentation of CMV retinitis due to delayed presentation. Screening for CMV retinitis, irrespective of CD4 counts, may help in developing nations. [ABSTRACT FROM AUTHOR]

Effective vaccine design relies on accurate knowledge of protection against a pathogen, so as to be able to induce relevant and effective protective responses against it. An ideal Human Immunodeficiency virus (HIV) vaccine should induce humoral as well as cellular immune responses to prevent initial infection of host cells or limit early events of viral dissemination. A Phase I HIV-1 prophylactic vaccine trial sponsored by the International AIDS Vaccine Initiative (IAVI) was conducted in India in 2009.The trial tested a HIV-1 subtype C vaccine in a prime-boost regimen, comprising of a DNA prime (ADVAX) and Modified Vaccine Ankara (MVA) (TBC-M4) boost. The trial reported that the vaccine regimen was safe, well tolerated, and resulted in enhancement of HIV-specific immune responses. However, preliminary immunological studies were limited to vaccine-induced IFN-γ responses against the Env and Gag peptides. The present study is a retrospective study to characterize in detail the nature of the vaccine-induced cell mediated immune responses among volunteers, using Peripheral Blood Mononuclear Cells (PBMC) that were archived during the trial. ELISpot was used to measure IFN-γ responses and polyfunctional T cells were analyzed by intracellular multicolor flow cytometry. It was observed that DNA priming and MVA boosting induced Env and Gag specific bi-functional and multi-functional CD4+ and CD8+ T cells expressing IFN-γ, TNF-α and IL-2. The heterologous prime-boost regimen appeared to be slightly superior to the homologous prime-boost regimen in inducing favorable cell mediated immune responses. These results suggest that an in-depth analysis of vaccine-induced cellular immune response can aid in the identification of correlates of an effective immunogenic response, and inform future design of HIV vaccines. [ABSTRACT FROM AUTHOR]