Many public health officials have taken heart in early evidence that suggests infections from the omicron variant tend to cause less severe illness than other versions of the coronavirus. But another important question looms: whether infection with omicron, including breakthrough cases in vaccinated people, can result in long COVID-19 — the constellation of physical, neurological and cognitive symptoms that can last for months and impair people’s daily lives.
It is too early for scientists to know much about the relationship between omicron, vaccination and long COVID-19. Research from earlier in the pandemic does not yield definitive clues. Here is a sketch of what scientists have learned and the many questions still to be answered.