ABSTRACT
Omicron variant of SARS-CoV-2 emerged in southern Africa in November 2021, showing more mutations on the spike protein gene than other variants, high efficiency in transmission, immune evasion, causing a mild disease, mostly upper respiratory and low mortality. Its proximate parent is unknown. We argue that its evolutionary pathway was reverse zoonosis in rodents, acquiring rodent adaptation mutations and subsequently infecting humans as zoonosis - conceptually a 'deviant' with antigenic shift rather than variant with antigenic drift;its pathogenesis is modified by its cell entry pathway resulting in the absence of syncytia, low virus load, sparing lungs of pneumonia and hypoxia. [ FROM AUTHOR] Copyright of Current Science (00113891) is the property of Indian Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)
ABSTRACT
The Covid-19 pandemic is raging, taking heavy toll of lives and livelihoods. The need for safe and effective vaccine(s) is urgent. Vaccine research has progressed rapidly and a few vaccine candidates have passed trial Phases 1 and 2, confirming reasonable safety and immunogenicity parameters. They are ready for large scale Phase 3 trials to quantify protective efficacy, if any, and to detect uncommon but serious adverse effects, if any. These developments present unprecedented opportunities and challenges, scientific and ethical. Globally hundreds die every day due to Covid-19, and emergency/compassionate use of vaccine candidates that are ready for Phase 3 trials are likely to save lives. We perceive an ethical imperative to allow such vaccination for those at high risk of death and voluntarily make such informed choice - for them protection delayed will be tantamount to protection denied.