New data from South Africa suggests the Omicron variant spreads more than twice as quickly as the Delta variant, and that immunity from prior infection doesn't appear to protect a person very well against Omicron variant.

Why it matters: The findings are extremely preliminary, and there are still many open questions about how well vaccines work against the variant. But these initial breadcrumbs of data are helping the world begin to understand what it's up against.

Where it stands: It's going to be a while before we can draw any firm conclusions about Omicron.

• Until then, scientists will be racing to piece together whatever information they have, and policymakers will then have to make real-time decisions about how to apply that imperfect information.

Driving the news: A South African preprint study released Thursday — which hasn't yet been peer-reviewed — found that reinfection is around three times more likely with Omicron than it was with other variants.

• The study makes no assessment of whether Omicron can also escape vaccine-induced immunity or how well prior infections protect against severe disease.
• South African researchers also released an initial assessment, which also had not yet been peer-reviewed, of how fast Omicron is spreading compared to Delta. The variant's ability to get past the body's immune system is part of what's driving the variant's rapid spread, the NYT reports.

Experts caution that it's way too early to know for sure, but there are some signs that Omicron may not cause more severe disease than the other variants. Under the best-case scenario, it'd cause milder illness.

The bottom line: This early information underscores the importance of getting vaccinated, even if you've already had COVID.