What we know about Omicron so far, according to an infectious disease specialist

·7-min read

A week has passed since the new COVID-19 variant Omicron, first identified in early November by scientists in South Africa, was designated a “variant of concern” by the World Health Organization because of its several mutations that may affect how easily it spreads or the severity of illness it may cause.

According to the Centers for Disease Control and Prevention, about 40 countries now have confirmed Omicron cases, including the United States. On Wednesday, the first confirmed Omicron case was detected in California; now other states including Minnesota, Colorado, New York and Hawaii have confirmed cases as well.

CDC Director Rochelle Walensky said during a White House COVID-19 press briefing on Friday that “we are prepared and ready to rapidly recognize the Omicron variant.”

However, researchers around the world are racing to fully understand the threat that Omicron poses. Compared with previous variants, does it spread more easily, cause more severe cases and have the potential to evade 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 Thursday about what is known so far and what physicians have seen on the ground in South Africa. (Some responses have been edited for clarity.)

Yahoo News: What are some of the latest updates about the Omicron variant, including whether it has been found to make people more ill?

Dr. Monica Gandhi: We've known about Omicron for a week, but actually we have quite a few updates. So, in terms of the symptoms ... the World Health Organization said that it looks like the Omicron variant is causing more mild disease among those who are unvaccinated. Ninety percent of the people who are in the hospital with Omicron are unvaccinated in South Africa. That’s a really important point because that means vaccines protect against this variant. And those symptoms seem more mild, and they’re being described as more muscle aches, more fatigue. Actually, not as much cough or loss of taste and smell, which has really defined COVID-19 before. That’s what has been described so far in South Africa.

What do we know about COVID-19 vaccine protection against the Omicron variant?

In terms of the ability to evade the vaccines, I actually have to answer this in two parts.

What we’re seeing clinically is that 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 U.K., Canada, Portugal and the U.S. 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. Just the [recent Minnesota] case in the U.S. had symptoms for two days and now is completely fine. And there was no transmissibility of the [first] case, described in San Francisco from a traveler. They did contact tracing and no transmission from that particular person. That’s the clinical data. If you have mild symptoms or no symptoms, that pretty much means your vaccinations work. And then importantly, 90 percent of those in the hospital, again, in South Africa are unvaccinated or have had one dose of the vaccine.

So what's the immunology data? [Vaccines] induce antibodies, which we talk about a lot, because they're super-easy to measure. But actually 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, they are the recipe book to make more antibodies in the future if you ever see a variant in the future. What B cells do, if they see a variant in the future, think of it as a recipe. 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 they'll adapt to the variant they see.

And then T cells — the way to think of that 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, if they 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.

What do we know about how transmissible Omicron is?

In terms of transmissibility, actually, that's the only thing that has happened with the variants. That's the only change. What I mean by that is that the ancestral strain — there was actually an old variant in the past that we never talk about, 614G, that actually was more transmissible than the Wuhan ancestral strain.

Then the Alpha strain, which was first identified in the U.K., was also more transmissible than the ancestral strain. And then the Delta variant, which was first identified, at least, in India and seemed much more transmissible than the Alpha variant. 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: Mu variant, Lambda variant, R.1 variant, Delta-plus variant and even the Omicron variant. I don’t think we’re convinced yet that this is more transmissible than Delta. We’ve described this for a week, so it’s not very long. But Botswana, for example, is [identifying] all its cases right now [as] Omicron, but the cases aren’t going up. And it looks like actually, from wastewater analysis in South Africa, it’s actually been 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’s actually not convincing evidence that Omicron’s more transmissible.

What should Americans be advised to do now that Omicron cases are in the U.S.?

Now that we have a week’s worth of data, I actually don't think really anything should change for vaccinated individuals. And two doses seems to be working well in, at least, 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 those who I really stress need 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’ll just help you prevent even a mild case of COVID. You don't want that around an immunocompromised individual, and of those who are developing severe breakthroughs, it’s more likely to be older people or immunocompromised people. So that’s what I would advise on the boosters.

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 percent at least first-dose vaccination rate in the United States. Many places are above 80 percent vaccination where I live, in the Bay Area.

We now have a year’s worth of data on these vaccines. Remember, they came out Dec. 14, 2020. They’re safe and effective. And I would really urge the people who are on the fence to get vaccinated.

I don’t think that we're going to see an increase in cases or hospitalizations except in places with lower rates of vaccination, and so I think the mainstay of fixing this problem is vaccination.

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