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Lambda Variant Could Be Vaccine Resistant, Study Finds

A woman with a t-shirt that says "I'm so tired" while getting vaccinated

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Key Takeaways

  • A new study found that the Lambda variant is highly infectious and may be more vaccine resistant than the original strain of COVID-19.
  • Previous studies also found that COVID-19 vaccines are less effective against the Delta variant.
  • Experts say vaccinations remain the most effective way to prevent against the virus and future mutations.

Similar to the Delta variant, the Lambda variant may be more infectious and vaccine resistant, according to a recent study in Japan.

The preprint study, which has yet to be peer-reviewed, shows that the Lambda variant is capable of bypassing the neutralizing antibodies that can fight off the virus. Researchers said that multiple mutations in spike protein, like those found in Lambda and other variants, are more resistant to antibodies in vaccinated and unvaccinated individuals. The researchers were able to demonstrate this in a lab setting.

Robert Quigley, MD, DPhil, senior vice president and global medical director at International SOS, tells Verywell that the findings are not surprising but should be observed critically.

“We're seeing a trend, which is what all of us in the scientific community expected, that the longer [COVID-19] is allowed to prevail, we're going to start getting towards vaccines that may not be efficacious against this SARS-CoV-2 viral variant,” Quigley says.

The researchers did not specify whether the Lambda variant was more dangerous than Delta. However, they pointed out that since the World Health Organization (WHO) designates Lambda as a Variant of Interest (VOI) rather than a Variant of Concern (VOC), people may not consider Lambda as an ongoing threat.

According to the study, Lambda’s virological features and how they evolve remain unknown. Other studies have also found that the Delta variant demonstrates some levels of resistance to the COVID-19 vaccines.

“You wouldn't want that combination of a virus that has the ability to spread really quickly... and it has vaccine resistance,” Quigley says. “That would be your kiss of death.”

Scientists will need to develop new vaccines when we reach that point, he adds. "The good news is that we’re not there yet," he says.

The Delta variant now accounts for more than 93% of COVID-19 cases in the United States, according to the Centers for Disease Control and Prevention (CDC). There are 938 COVID-19 cases caused by the Lambda variant, which is less than 1% of the nation’s total cases. The CDC currently has no information about Lambda on its variant classification page.

How Does a Virus Become Vaccine Resistant?


Viruses, or variants of viruses, can become vaccine resistant if they mutate. Mutations occur naturally so long as the virus has a host (a person) to infect and transmit infection from.

While not all mutations are vaccine resistant, those that are different enough from the original strain of the virus may not be neutralized by the appropriate antibodies. 

This is alarming, but not uncommon, Quigley says, adding that scientists also update the influenza vaccine to target new mutations every year. 

These decisions are decided by international health agencies, who work collaboratively with the CDC to decide what strains of influenza are circulating and how to combat them with vaccines, Quigley adds.

“Usually they're pretty close to being right, but it's not always 100%,” he says. “Some years, they’re not as efficacious as other years.”

If the virus sticks around longer, assembling a similar panel to survey mutations and develop subsequent COVID-19 vaccines will be important, he adds. Booster shots or a variant-specific vaccine are also important considerations going forward, he says.

“It's no surprise that we're seeing these variants,” Quigley says. “What is surprising to me is that we're not, as a society, taking advantage of the data we do know, which is that vaccinated people will stop this spread because there'll be no place for this virus to replicate.”

What This Means For You

A virus can mutate and change so long as it has a person to infect. Vaccinations are essential in reaching herd immunity and preventing mutations. You can find a vaccination clinic near you at vaccines.gov.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

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  1. Kimura I, Kosugi Y, Wu J, et al. SARS-CoV-2 Lambda variant exhibits higher infectivity and immune resistancebioRxiv. Published online July 28, 2021:2021.07.28.454085. doi:10.1101/2021.07.28.454085

  2. World Health Organization. Tracking SARS-CoV-2 variants. Updated August 4, 2021.

  3. Lopez Bernal J, Andrews N, Gower C, et al. Effectiveness of Covid-19 Vaccines against the B.1.617.2 (Delta) VariantNew England Journal of Medicine. 2021;0(0):null. doi:10.1056/NEJMoa2108891