If you’ve had omicron before, are you safe from infection by the new variants?

Michaeleen Doucleff | May 4, 2022
A woman wears a face shield to protect against COVID-19 at a taxi stand in Soweto, South Africa, where an omicron variant is causing a COVID-19 surge.
A woman wears a face shield to protect against COVID-19 at a taxi stand in Soweto, South Africa, where an omicron variant is causing a COVID-19 surge. Denis Farrell | AP

When it comes to omicron, one thing seems certain to bioinformatician Shishi Luo: Another surge will occur.

That’s because new versions of omicron are emerging — here in the United States and in other parts of the world as well, like South Africa.

These new variants have a key set of mutations which enable them to spread even faster than the previous versions of omicron.

So people are wondering: If I had omicron once, can I get it again?

Now two preliminary studies, published online this week, start to answer that question. And the results show just how quickly omicron can mutate and overcome the defenses our immune systems put up.

How the variants are faring in the U.S. and South Africa

Before we get to the studies, let’s look at what these variants are doing in the U.S. and South Africa.

In the U.S. a new version of omicron called BA.2.12.1 emerged in central New York state last month, where it caused a steep rise in cases. BA.2.12.1 is now found across the country, and It spreads about 50% faster each week than the omicron BA.2, which has been dominant in the U.S. variant.

“Given how this [new] variant is rising now in the U.S. it will definitely come to dominate here,” says Luo. “And so I think the question is how high will the surge go before it peaks? How big of a bump will it be? I don’t know the answer. It really just depends on people’s behavior.”

In South Africa, two of these new omicron variants, known as BA.4 and BA.5, are causing a fifth wave of cases. In the past two weeks, cases there have nearly quadrupled, from about 1,200 each day to 4,600 each day. And the positivity rate jumped from about 8% to 18%.

Omicron is a ‘master player’

What these new variants show is just how wily omicron is.

“In terms of the ability to evade antibody activity, omicron is a master player. It’s way more efficient than all the previous variants,” says virologist Pei-Yong Shi at the University of Texas Medical Branch at Galveston, who wasn’t involved in the newly published studies. “Like in this case, you need just a key mutation that can totally flip things around.”

The two new studies start to explain why, all of a sudden, these new variants have started to spread so quickly. The answer boils down to one key factor: Their mutations allow them to re-infect people who have already had an omicron infection. This reinfection risk may be higher for people who are not vaccinated.

In the studies, researchers took blood from people infected with the original omicron variant, BA.1, and looked to see if the antibodies in the blood could neutralize newer versions of omicron, including the one that emerged in New York state (BA.2.12.2) or the two variants surging in South Africa (BA.4 and BA.5).

All people infected with omicron BA.1 had antibodies able to neutralize BA.1. But that potency decreased dramatically against the new variants (BA.2.12.2, BA.4 and BA.5). And how much it declined depended heavily on whether the people were vaccinated.

For people not vaccinated, their antibodies ability to neutralize BA.4 and BA.5 dropped by nearly 8 times, compared to the activity against BA.1, both studies reported.

“Neutralization capacity … after BA.4/5 was very low,” immunologist Alex Sigal, who led one of the studies, wrote on Twitter. Against BA.2.12.1, the potency dropped by about 4 times, researchers at Peking University reported.

“Together, our results indicate that Omicron can evolve mutations to specifically evade … immunity elicited by BA.1 [omicron] infections,” biophysicist Sunny Xie and his colleagues from Peking University write in one of the studies.

What vaccines can and can’t do

“The situation was better in the vaccinated breakthrough cases,” added Sigal, who’s at the Africa Health Research Institute. For people immunized, either with the Pfizer vaccine or the Johnson & Johnson vaccine, the neutralization ability dropped only 3 fold against BA.4 and BA.5, compared to the potency against BA.1. These people also had more neutralization capacity against BA.1 to begin with. So in the end, they had, on average, about 5 times the neutralization potency against the new variants, compared to people who weren’t vaccinated before the infection.

“The data shows, again and again, that the vaccine still has tremendous benefits,” says virologist Pei-Yong Shi in Galveston, Texas.

Nevertheless, Sigal believes this decline in antibody potency is enough “to cause trouble and lead to an infection wave” – like in South Africa, where only about a third of the population is immunized.

Bioinformatician Tulio de Oliveria agrees. “Previous infections with Omicron BA.1 will not be sufficient to prevent a second infection with BA.4 and BA.5,” de Oliveria, who’s at the Center for Epidemic Response and Innovation in Durban, wrote on Twitter.

“Some scientists & science communicators are convinced that one needs a new variant to cause a new wave,” de Oliveira added. “Delta caused a long wave with multiple lineages. Omicron is causing waves with BA.1, BA.2, BA.2.12.1, BA.4 & BA.5.”

Here in the U.S., both BA.4 and BA.5 are extremely rare. No one knows if they will be able to compete with BA.2.12.2, which accounts for about a third of all cases in the U.S., the Centers for Disease Control and Prevention estimates. “Cases of BA.2.12.2 are growing exponentially,” says Shishi Luo at Helix. “Depending on the rate of that exponential growth, we could start seeing a really sharp increase in cases across the country happening in the next month or so.”

Copyright 2022 NPR. To see more, visit https://www.npr.org.

Transcript :

ARI SHAPIRO, HOST:

For a few months, it looked like COVID-19 was retreating in the U.S. Daily case counts were declining across the country at the lowest they had been since last summer. But COVID cases are now taking up again, and scientists are concerned that a new variant may cause another surge.

NPR’s Michaeleen Doucleff is here to tell us about it. Hey, Michaeleen.

MICHAELEEN DOUCLEFF, BYLINE: Hi, Ari.

SHAPIRO: Cases are still low across the U.S. overall, but tell us about this new variant that scientists are concerned about. What do they know about it?

DOUCLEFF: Yeah. So about a month ago, New York state was having a mini surge, especially in the center part of the state. And health officials found that the cause of that surge was a new variant. It has a complex name. It’s called BA.2.12.1. It’s a mouthful. And it’s a new version of omicron. Basically, the omicron variant picked up several mutations that give it an advantage and help it spread faster than the previous version, about 50% faster.

SHAPIRO: And so where is it now and how likely is it that this is going to cause another surge?

DOUCLEFF: Yeah, it’s most common in New York, New Jersey and the mid-Atlantic States, but it’s present throughout the whole country. And given its current trajectory, it will likely dominate the outbreak here in the U.S. within a month or so.

In terms of whether it will cause another wave, I was talking to Shishi Luo about that. She’s a bioinformatician at the company Helix, which tracks variants across the country. She says there’s little doubt that this new variant will cause a surge in cases.

SHISHI LUO: Because the current trajectory is that it’s growing, and we’re seeing rises in new cases, and we’re seeing wastewater levels go up. So I think the question is how high will it go before it peaks? I don’t know the answer to that. It really just depends on people’s behavior and the weather how big of a sort of bump it is.

DOUCLEFF: So this bump or surge she’s talking about will likely occur in about a month or two, she says.

SHAPIRO: So you’re telling me that if last summer vacation was all about the delta variant vacation, this summer is going to be BA.2.12.1?

DOUCLEFF: Yes. It might get another name by then, but yeah. And, you know, this prediction is supported with – by what’s happening in South Africa right now. That country has a new variant – or two variants that are very similar to the one here in the U.S. And it’s already causing a surge there. And the U.S. tends to be about six weeks behind that country. Fortunately, though, scientists don’t think this next wave will be as big as the surge we had last summer – or sorry – last winter, which perhaps, you know, half of Americans called omicron back then.

SHAPIRO: But if half of Americans caught omicron last winter and so many Americans have been vaccinated, how could a version of omicron cause a surge when so many Americans are protected?

DOUCLEFF: You know, that is a really great question. And two preliminary studies that came out this week start to answer it. And what these studies found is these new versions of omicron, both here in the U.S. and in South Africa, picked up just a few mutations that allow them to overcome or evade immune protection generated by a prior infection with omicron. So these new variants likely can reinfect people who have already had omicron.

I was talking to Pei-Yong Shi about this. He’s a virologist at the University of Texas Medical Branch in Galveston. He says omicron is really unique because it has an incredible ability to change or evolve in a way that allows it to just zoom past the immune system, and it does this very quickly.

PEI-YONG SHI: In terms of the ability to evade antibodies, omicron is a master player. It’s way more efficient than all the previous variants. Like, in this case, sometimes you just need one key mutation there that can totally flip things around.

DOUCLEFF: But Shi emphasized that there’s no sign this new variant causes more severe disease compared to the previous omicrons.

SHAPIRO: Well, that’s good news. How about the effectiveness of the vaccine against this new variant?

DOUCLEFF: You know, generally, the vaccine probably won’t offer much protection against infection, especially over the long term. But scientists do think it will still offer excellent protection against severe disease and hospitalization. But you do need the booster – so three doses of the mRNA vaccine. And if you’re over age 50, health officials recommend you get a fourth dose, or a second booster, about four months after the first one. That will give you a little more protection against severe disease, especially if you’re at high risk. So Ari, really, you know, the hope here is that although cases will probably surge again at some point – maybe this summer – hospitalizations won’t because, as you said, the majority of Americans now have some protection.

SHAPIRO: Here’s hoping. NPR’s Michaeleen Doucleff. Thanks for the update.

DOUCLEFF: Thank you, Ari. Transcript provided by NPR, Copyright NPR.