Is the Omicron mutant more highly contagious, and will the current COVID-19 vaccines protect effectively against it?

It is not more highly contagious per se, but it will be as infectious as other strains and that makes it dangerous, because even the old strains can reinfect prior patients with the illness, from a breakthrough infection owing to inadequate immunity. We explained at the outset of the pandemic that this class of viruses is notorious for difficult vaccination as a containment or a preventative strategy because it is highly mutable, and that makes it difficult to keep up with. But even with relative stability, vaccination will not be a perfect answer due to the fact it is better at preventing severity of illness than infection, which might take place regardless of vaccination status and allow the spread, so that makes the unvaccinated more in danger all the way around from the new mutant or prior strains of the virus. The COVID-19 vaccines currently in use will confer protective immunity that is sufficient to be worthwhile. So it has not been possible to produce a mutant that will be undetected by the immune defenses, ramped up by prior infection of the previous strains. It remains to be seen whether that will continue to be the case.