The last thing people wanted to hear the day after Thanksgiving was that a new, scary coronavirus variant was on the loose. Alas, we don’t get to choose what the virus will do next, so we need to learn what we can about this new variant and what it does—and doesn’t—mean for us. There is good news, though: the new variant, named Omicron after the next available letter in the Greek alphabet used to name variants, has been detected relatively early. Fewer than 200 cases have been identified, and none are in the US so far. Scientists have been doing excellent work with surveillance, especially in South Africa, where the variant was first detected, and public health officials expect to have a lot more information about the variant within the next three to four weeks. That may feel like a long time in Covid days, but it’s practically warp speed in scientific research time. Here’s what we know so far.

Where Is Omicron?

The first cases were identified in South Africa, but that doesn’t necessarily mean that’s where the variant arose. South Africa has one of the best virus surveillance programs in the world, so, unsurprisingly, they found it with so few cases circulating so far. Cases have also been identified in Botswana, the only country with person-to-person local transmission. Other countries with cases include Canada, Australia, Hong Kong, and several Western European countries, all of which have identified incoming travelers with Omicron infections. There may already be Omicron cases in the US, but none have been identified.

Why Are Scientists Worried About Omicron?

Sometimes, it’s the devil you know that scares you most, and sometimes it’s the devil you don’t know. With Omicron, it’s a bit of both. Omicron has a little over 30 mutations in the spike protein, the part of the virus that the immune system uses to recognize the pathogen as an intruder and mount a defense against it. Scientists are familiar with a little over half of these mutations because they’ve seen them in other variants, including Delta, Alpha, Beta, and Gamma, and it’s concerning to see so many familiar mutations in one variant.

Some of these mutations can make the disease more severe, some increase its transmissibility, and some may reduce the effectiveness of existing immunity (from the vaccine or a prior infection) in fighting off a new infection. Having all those tools in one virus’s arsenal is not ideal. As for the other mutations, scientists don’t yet know what they mean. They could mean nothing or give the virus an edge in infecting people—we have to wait for more information.

Does That Mean the Vaccines Won’t Work Against Omicron?

This appears to be the biggest concern that has people wondering. The short answer is that we don’t know yet, but there are reasons to be concerned and hopeful. First, the bad news: some of the mutations on Omicron were seen on Beta that helped that variant avoid antibody binding in the lab. In other words, when scientists tested antibodies from the vaccine against the Beta variant in a Petri dish, the antibodies didn’t bind as well to the virus as they did for other variants. That suggests the vaccine’s effectiveness would be lower—but not useless—against Beta. Still, Beta never took off well enough for us to gather good clinical data confirming that one way or the other.

But here’s the good news: the human immune system can adapt quickly to new threats when it has a head start. Anyone with preexisting immunity to SARS-CoV-2, whether from the vaccine or past infection, will have B cells that “remember” how to fight the virus. B cells are the immune cells that produce antibodies. While the body’s existing antibodies can’t change to something new for the new variant, the B cells can adjust how they make the antibodies once they “see” the new variant. That means vaccination still offers some protection against Omicron, even if we don’t know how much yet.

What Does Omicron Mean for Me and My Patients?

Right now, Omicron doesn’t change anything about public health recommendations or the threat of Covid infections to people in the US. Delta infections continue to be high, and public health officials expect a winter surge, especially because more people get together indoors. Covid vaccination is still the best defense against SARS-CoV-2 infections, including getting a booster dose for those fully vaccinated for at least six months. Other recommendations remain the same: advise people with symptoms to isolate and get tested, wear a mask indoors around people from outside your household, use social distancing as much as is reasonably possible, and improve ventilation wherever it is possible by opening windows and doors or adding HEPA filters to the room.