How worried should we be about the Lambda variant?

Maxine McCrann

The Delta coronavirus variant has taken center stage in the Hot Vax Summer that wasn't. But as if this highly contagious variant and the public health guideline changes it’s helped spur weren’t concerning enough, other variants are lurking in the wings. The Lambda variant in particular has generated significant buzz as of late. Mic spoke with medical experts about what we know about Lambda so far — and how much we need to worry about it.

What is the Lambda variant?

We should preface all of this by saying that scientists still have a lot to learn about Lambda. At this point, though, we know that it was first detected in Peru last August, says Jeff Pothof, the chief quality officer and emergency medicine doctor at UW Health in Madison, Wisconsin. Although most prevalent in South America, it’s been detected in 29 countries, including the U.S., Newsweek reported. According to the GISAID Initiative, which provides epidemic and pandemic virus data, Lambda has accounted for only about 1,000 cases in the U.S. as of this writing. (In contrast, the WHO announced that Delta is in 135 countries, MarketWatch reported. According to the CDC, more than 93% of cases in the U.S. could be attributed to Delta as of the end of July.)

The WHO has labeled Lambda a “variant of interest,” a less serious designation than a “variant of concern.” Raywat Deonandan, an epidemiologist at the University of Ottawa, told CTV News that a variant of interest is "suspected" to be more easily spread than the O.G. version of the virus, make people sicker, and circumvent vaccines. If evidence piles up that it checks off one or more of these boxes, the WHO can upgrade it to a variant of concern, Deonandan explained. The CDC, on the other hand, hasn't listed Lamdba as either a variant of interest or a variant of concern. Both the WHO and CDC list Delta as a variant of concern.

Structurally, Lambda reminds Pothof of Alpha, first seen in the U.K. late last year, “so it certainly has the ability to be a bit more infectious” than the original version, he says.

How does Lambda stack up against Delta?

There’s not a whole lot known about the transmissibility of Lambda compared to that of Delta, but based on the spread we’ve seen of each variant so far, “Delta is far more successful as a variant, period,” Emily Landon, an associate professor of medicine at UChicago Medicine, who specializes in infectious diseases. Although it’s taken off in South America, especially Peru (where it reigns as the dominant strain, per Newsweek), that just hasn’t been the case in the U.S., even if it's existed since at least last August.

“If it was racing Delta to take over, it didn’t win,” Landon points out. It seems that “there’s something about South America" — whether the vaccines they're using, the variants they had earlier on, and/or something else entirely — “that offered an opportunity for Lambda to go through an open door and cause lots of problems.” Lambda, on the other hand, doesn’t seem able to take advantage of the opportunities here in the U.S. to become dominant. That could partly be because "Delta is smothering it,” Landon explains.

As you can see on GISAID's maps of variant occurrence, “everywhere [Delta] lands, it turns into problem,” she says.

Pothof agrees. “In general, at this point in the game, early August, Lambda has me less concerned than Delta,” he tells Mic. He notes that "we don't have definitive studies on Lambda transmissibility." But based on the fact that it resembles Alpha more than Delta, he believes it'd be reasonable to guess that it's more contagious than the original virus, but not as contagious as Delta, at least until we see a study that gives us better data.

"I think the jury's not out yet" on whether Delta makes you sicker than earlier variants, he says. The variant "is likely more severe," per the CDC. But while it seems like it is, since it’s been seen in so many of those hospitalized, Pothof suspects that this could also just be a function of the fact that Delta is so contagious and therefore, widespread. Meanwhile, those who were, say, stuck at home with only mild symptoms due to Delta might've been harder to count.

“I think the same thing will hold with Lambda,” Pothof says. “It’s a little bit better at infecting people, so it might look like it makes people more sick, but I would say there’s no conclusive evidence at this point that it actually causes more severe disease.”

Do the vaccines protect against it?

Some people who’ve become infected with Lambda have been vaccinated, Landon says, raising concerns that it may be able to evade the immunity created by vaccines, “but I think all of that is sort of preliminary right now.”

Recent laboratory findings that Lambda has spike protein mutations that help it resist neutralization to the antibodies the body makes in response to vaccination have also caused worry. It's important to note, though, that observations made in lab-grown cells don't necessarily reflect what happens in the real world. Also, the researchers described their results in a preprint — basically, a paper that hasn't yet gone through the stringent peer review process required for publication in a scientific journal.

Indeed, Pothof says that “we don’t have good studies” on whether Lambda can significantly disrupt the vaccines’ ability to neutralize it. And he adds that we don’t have a study, period, that calculates the effectiveness of the antibodies created by each of the three vaccines currently available in the U.S. against Lambda. But in the absence of such a study, given that Lambda is similar to Alpha, we can infer that the vaccines will be as effective against Lambda as they were against Alpha — which was, thankfully, pretty effective, Pothof says.

So, how worried do I need to be about it?

Both the experts Mic interviewed agree that while it's not clear what'll become of Lambda, we need to be concerned about it and see what it does. “Not every variant is going to be a problem for us,” Pothof says, but keeping an eye on them ensures that they don’t catch us by surprise. The last thing we want is a spike in another highly contagious variant before we have an action plan in place and see cases spiral out of control.

When predicting how a variant will impact the U.S., Landon says it’s helpful to look at variants in parts of the world that resemble ours in terms of factors like societal structure, healthcare, COVID restrictions, and vaccination rates. She points out that Alpha and Delta, which swiftly spread across the U.K. — a region in many ways similar to the U.S. — also ended up causing trouble here. But Peru, ravaged by Lambda, is “a completely different kind of situation than what we have here,” Landon says.

She believes that we need to focus more on amping up vaccination rates, rather than getting too worked up over the Next Scary Variant. While a lot of people are vaccinated, there are enough unvaccinated people for the virus to spread quickly — including to vaccinated people, she explains, especially given that Delta is so transmissible.

Remember that while the vaccines are highly effective, they aren’t perfect. Every once in a while, a virus with a mutation will arise in an infected, vaccinated person that’ll allow it to evade the immune response triggered by the shot (although because the vaccines work so well, they'll have a much lower risk of becoming seriously ill or dying), Landon tells Mic. Basically, the "selective pressure" from the strong immune response to the vaccines will push the virus to mutate into hardier variants.

“I think the point is, until we get to a place where we have enough vaccinated individuals to really shut down the spread of the virus significantly, we’re not going be able to easily deal with any dangerous variant that comes next,” Landon says.