Here’s what we know about Omicron so far, according to an infectious disease specialist

It’s been about a week since Omicron (B.1.1.529), a new SARS-CoV-2 variant, was designated a “variant of concern” by the World Health Organization. Researchers around the world are racing to fully understand the potential threats Omicron poses regarding its transmissibility, its virulence and its potential to evade the COVID-19 vaccines. Dr. Monica Gandhi, infectious disease specialist and professor of medicine at the University of California, San Francisco, spoke with Yahoo News on Dec. 2 about a few updates on Omicron and what physicians have seen on the ground in South Africa.

Video transcript

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MONICA GANDHI: So we've literally known about omicron for a week, but actually we have quite a few updates in terms of the symptoms. At least those physicians who are working, again, on the ground in South Africa, and then they report their information into the World Health Organization, who is responsible for talking about this variant. The WHO said that it looks like the omicron variant is causing more mild disease among those who are unvaccinated. 90% of the people who are in the hospital with omicron are unvaccinated in South Africa. That's a really important point, right, because that means vaccines protect against this variant.

And those symptoms seem more mild, and they're being described as more muscle aches or fatigue, actually not as much cough or loss of taste and smell, which has really defined COVID-19 before. So that's all we know so far. That's what has been described so far in South Africa.

In terms of the ability to evade the vaccines, I actually have to answer this in two parts. One is what are we seeing clinically? Well, what we're seeing clinically is that, frankly, of course, when a variant is described in a country, you suddenly start seeing it everywhere. This is a highly transmissible respiratory virus. Travel bans cannot change that. And it was described very quickly in Denmark, the Netherlands, Israel, Italy, the UK, Canada, and the US. And all of these cases tend to be vaccinated individuals because these are places that have had high access to the vaccines, and either vaccinated individuals are asymptomatic or have very mild symptoms.

So that's the clinical data, right? If you have mild symptoms or no symptoms, that pretty much means your vaccinations work. And then importantly, 90% of those in the hospital in South Africa are unvaccinated or have had one dose of the vaccine.

So what's the immunology data? The way I think about immunology to explain it is what the vaccines do is they induce three things. Think about it that way. They induce antibodies, which we talk about a lot because they're super easy to measure, but they also induce what's called cellular memory or immune cells that serve as templates to help us later. So one is called B cells and one is called T cells.

And the way to think about B cells is-- I just think this is the simplest way to explain it. They are the recipe book to make more antibodies in the future. They're not going to make antibodies against an old strain. They actually are going to adapt their antibodies to fight the variant that they see in front of them.

Say you're in a high-altitude region and you need to add more yeast to your recipe. They know that's what a recipe does. It changes with the circumstances. And so B cells are actually aided by T cells to make antibodies now adapt to the variant they see.

And then T cells, the way to think of that really simply is there are a bunch of T cells that line up across the spike protein. Yes, the omicron variant has 32 mutations across the spike protein, but there may be up to 90 T cells that line up against the spike protein. You change 32 of them. You have 60 left that fight the virus as we see it.

So it's hard to evade the vaccines by a variant. And now I think we have a really good consensus that omicron doesn't look like it's going to evade the vaccines.

So the only thing that the variants have seemed to change about anything about COVID-19 is making it more transmissible, and that has implications because it can spread faster. And we saw that with the delta variant, but no variant that has emerged since the delta variant-- nu variant, lambda variant, R1 variant, delta plus variant, and even the omicron variant I don't think we're convinced yet that this is more transmissible than delta. A week-- we've described this for a week, so it's not very long, but Botswana, for example, are describing all its cases right now are omicron, but the cases aren't going up. And it looks like actually from wastewater analysis in South Africa, it's been actually in South Africa for a while. It's been in Europe for a while. And in many places that are highly vaccinated, we're not seeing cases go up. So there is actually not convincing evidence that omicron's more transmissible.

Now that we have a week's worth of data, I actually don't think really anything should change for vaccinated individuals. And two dose seems to be working well in South Africa where they haven't rolled out universal boosters.

And this is what I would advise for Americans. If you're fully vaccinated, you're great. I would say that for those who I really stress the need for boosters would be those over 65, those who are immunocompromised, those who have multiple medical conditions that are under 65, or if you are an individual who's going to be around someone who's immunocompromised. Those are the four groups I would really be stressing that they should get a booster because that will just help you prevent even a mild case of COVID. You don't want that around an immunocompromised individual. And those who are developing severe breakthroughs, it's more likely to be older people or immunocompromised people.

In terms of unvaccinated, what we saw with the delta variant, which was more transmissible, is that actually there were massive rises in cases and hospitalizations in more unvaccinated regions in the United States. We are in a better place than we were with the delta variant, which became very dominant in this country in July. We're now in December. We're at a 70% at least first-dose vaccination rate in the United States. Many places are above 80% vaccination. Where I live in the Bay Area, I doubt anything's going to change for the unvaccinated here with the omicron variant.

But I would say that if you're unvaccinated, again, I'm always-- and many would urge you to get vaccinated. We now have a year's worth of data on these vaccines. Remember, they came out December 14, 2020. They're safe and effective, and I would really urge the people on the fence to get vaccinated.

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