How worried should we be about Lambda variant of coronavirus?

Dr. Anita Sircar examines a COVID-19 patient inside Little Company of Mary Medical Center.

Aug. 18, 2021 Updated 7:39 AM PT

Throughout the pandemic, the coronavirus has spawned a multitude of mutations: from the once-dominant Alpha variant to the still-raging Delta strain.

But with California and the country still in the grips of another COVID-19 surge, a new alphabetized entry — Lambda — has been raising fresh questions about whether it, too, might feature characteristics that could trigger dangerous shifts in the dynamic pandemic landscape.

Lambda, which was first identified in Peru, is worth watching because “it has had massive spread in South America,” according to Dr. Benjamin Pinsky, director of the Clinical Virology Laboratory at Stanford University.

“But we don’t know at the moment whether this will be something that will supplant Delta,” he said in an interview.

Despite its growing prominence in the public consciousness, Lambda isn’t considered a variant “of concern,” according to the World Health Organization — a designation reserved for the Alpha, Beta, Gamma and Delta coronavirus strains, which were first identified in Britain, South Africa, Brazil and India, respectively.

Lambda is instead in a lower tier — a variant “of interest” — that the WHO considers worth watching but is of less concern for now.

That’s not to say Lambda “is less important, by any means. It is one that we are actively discussing and we are actively trying to gather and garner as much information as we can from all available sources,” said Maria Van Kerkhove, WHO’s technical lead for COVID-19.

“There are several mutations in the Lambda variant in the spike protein, there are some amino acid deletions, there’s a number of characteristics of it that caused some concern because, of course, any changes in the virus pose some threat to its ability for the vaccines to work,” she said during a briefing.

So far, the Centers for Disease Control and Prevention has not named Lambda a variant of interest or concern in the United States — and cases are not being publicly tracked on the agency’s website.

One reason Lambda has attracted attention is that it has a mutation known as L452Q, which is similar to a mutation known as L452R that has been found in the Delta variant and the so-called California variant, also known as the Epsilon variant, Pinsky said.

When exposed to an immune system that has received a COVID-19 vaccine, the presence of the L452R mutation in the coronavirus has been shown to reduce — by threefold — the effectiveness of antibodies to prevent the entry of viruses into the body’s cells, Pinsky said.

The good news, however, is that the vaccines have so far still been effective at reducing the chance of severe illness and death, even in variants with this mutation, including Delta.

Data cited by Dr. Anthony Fauci, the U.S. government’s top infectious disease expert, now show that each of the vaccines authorized for use in the U.S. — Pfizer-BioNTech, Moderna and Johnson & Johnson — all have evidence of clinical effectiveness against the Delta variant.

So-called breakthrough infections, cases in which people are infected despite being vaccinated, can be expected because no vaccine is 100% effective, Fauci said last week. But they overwhelmingly do not result in severe illness or death.

A study Fauci cited, which came out from South Africa and other nearby countries and involved about 478,000 healthcare workers, showed real-world effectiveness of the Johnson & Johnson vaccine against the Delta variant, with 91% to 96% protection against death and 71% protection against hospitalization.

“As we’ve seen in other studies, the breakthrough infections — namely infections that occur in the setting of full vaccination — were mild in 96%, moderate in 3%, severe in less than 0.05%, with death in less than 0.05%,” Fauci said.

While none of the variants that have emerged have dramatically pierced the effectiveness of vaccines, Pinsky said such a possibility can’t be ruled out.

“We need to be prepared for the potential that this virus could mutate to evade existing vaccines,” Pinsky said. But the latest vaccine technology is promising such that vaccines can be rapidly updated to address changes in the coronavirus, he added.

Experts say there are not much data now to suggest Lambda will replace Delta as the dominant strain in the U.S.

“I don’t think there’s evidence at the moment that this is going to be the virus that evades our immune system,” Pinsky said of Lambda. Still, “as always, it’s important to be cautious with this virus. We have not been good at predicting.”

So far, data show Lambda has yet to spread nearly as widely as Delta.

There are at least 152 documented cases of the Lambda variant in California, according to the state Department of Public Health. Delta, by comparison, has caused 69 times as many confirmed infections despite emerging in the state months later.

In L.A. County, there has been only one Lambda case identified, from a sample analyzed in June, Public Health Director Barbara Ferrer said during a recent briefing.

While not every new coronavirus infection is subjected to variant-determining sequencing, all indications are that Delta is, by far, the most dominant in the U.S.

It is estimated to represent more than 97% of cases over the last two weeks of July, according to the CDC.

In California, nearly 91% of coronavirus cases analyzed in July were identified as the Delta variant, state figures show. And last week, that variant constituted virtually all of the sequenced strains in Los Angeles County.

Delta’s dominance shows how the variants of the coronavirus can dramatically change from month to month. The strain that caused the first cases in the U.S. is essentially extinct nationwide, and the Alpha variant — which was first detected in the United Kingdom and also spread rapidly because of its increased transmissibility — went from representing an estimated 70% of coronavirus cases in May to less than 1% today.

Of the 152 Lambda cases that have been detected in California so far, 88 of them were sequenced in April, the same month the Delta variant got its initial toehold in the state.

Since then, the monthly tally of sequenced Lambda cases has plummeted — to 43 in May, eight in June and only two in July, according to state health officials.

Whether Delta may eventually be elbowed out by other variants, such as Lambda, is of keen interest in the public health realm.

“What we’re looking at is how well it circulates — how much transmission takes off once the variant is detected,” Van Kerkhove said.