Scientists around the world are racing to understand the Omicron variant, and there are some clearer signs than a week ago.

Does Omicron spread faster than earlier variants.

It’s still possible that this will be a mirage — and that the world is confusing a more normal surge in cases with the effects of a new variant.

(Surges do often happen for mysterious reasons.) But the evidence for faster spread of Omicron seems strong.

“The data out of South Africa suggest that the Omicron variant is spreading more quickly than Delta,” Janet Baseman, an epidemiologist at the University of Washington, told me.

The first is that Omicron is more contagious in a technical sense — that it spreads more rapidly among people with no immunity than earlier variants did.

The second is known as immune evasion; it describes the notion that vaccinated people and those who were previously infected contract Omicron more often than they contracted earlier versions of the virus.

Is Omicron more severe than earlier variants.

Some scientists think it’s simply too early to know whether the average person who contracts Omicron becomes sicker than the average person who contracted earlier versions of the Covid virus.

Severe Covid illness often takes a week or more to develop, and the world has been aware of Omicron for less than two weeks.

The initial studies of Omicron patients have also come disproportionately from South Africa, where the population skews young and many people were previously infected with Delta.

“What is hard to assess right now,” Jennifer Nuzzo of Johns Hopkins University said, “is how this will play out if or when older and more vulnerable people become infected.”.

Either way, I think it’s a mistake to assume that Omicron is more severe than earlier versions of the virus — as people often do when they hear about a new variant.

So are vaccinated people protected or not.

The answer depends on the meaning of “protected.” Is it protected from any Covid infection — or from severe illness.

The evidence so far suggests that Omicron may be more likely to infect vaccinated people than earlier versions of the virus, as I mentioned above.

Yet there is still no sign that Omicron will cause a significant share of vaccinated people to get severe versions of Covid.

The situation may be similar for unvaccinated people who have had a prior infection — or they may be more vulnerable than the vaccinated to serious Covid.

One worrisome postscript is that even seemingly mild Covid infections can prove deadly for vulnerable people, like the elderly.

A second problem is that immunity among the vaccinated and previously infected really does seem to be waning over time.

For now, vaccinated people can reasonably continue to behave as they were — but many should feel urgency about getting booster shots.

Older people and others who are vulnerable, like people receiving cancer treatment, should continue to be careful and ask people around them to test frequently.

About 1,000 Americans have been dying each day of Covid in recent weeks, the vast majority of them unvaccinated.

The Omicron variant.

Omicron appears to spread rapidly, though it may be less severe than other forms of the virus.

Mayor Bill de Blasio announced a sweeping vaccine mandate for all private employers in New York City to combat the spread of the Omicron variant.

New Covid treatments.