Quartz: “The omicron variant of covid-19, which has replaced delta as the most common strain, is still spreading around the world. While it’s much more contagious than previous covid-19 variants, omicron carries two possible silver linings: It appears to be less likely to cause severe illness and its spread raised some hopes that it could help create herd immunity in areas of low vaccination rates. This, for instance, is what prompted the World Health Organization’s European office to publish a statement saying omicron might open a new phase in the pandemic, with widespread immunity reached through a combination of vaccinations and infections. Yet new research published Jan. 26 by researchers at the University of California, San Francisco shows the long-term effect of omicron-induced immunization might be highly overrated…”