A person wears a face mask on the London underground, as the spread of the coronavirus disease (COVID-19) continues in London, Britain, Nov 29, 2021Experts say that the Omicron variant could dash any lingering hopes of populations reaching herd immunity against COVID-19, after a preprint study from South Africa suggests the highly-mutated strain is more capable of reinfecting people than previous strains. South African researchers have found that Omicron is 2.4 times more likely to reinfect s...