News & Resources
August 18, 2021

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The SARS-CoV-2 Lambda Variant

COVID-19 Resources
On behalf of the Emerging Infectious Disease Task Force & David Hogan, DO, MPH, FACEP, Vice President of Educational Development, Chair TeamHealth Emerging Disease Taskforce, Director of TeamHealth Academic Consortium


As expected, the SARS-CoV-2 virus continues to evolve and new viral variants develop. The most recent is the Lambda variant as named by the World Health Organization (WHO). With this comes many questions. Why are there so many SARS-CoV-2 variants? What is the Lambda variant? And what can we expect for the remainder of the year?

The Viral Swarm and SARS-CoV-2 Variants

Like the influenza virus, the SARS-CoV-2 virus is not a single virus, but a swarm of varying viral strains. Each particular strain of the virus is a tiny bit different – like a swarm of bees. Some of them are a little tougher, some a little weaker, but overall they represent the viral swarm that is the pandemic.

On occasion, a “super bee” emerges that is fast, hard to run away from and has a painful sting.  Those are the major variants of concern or interest, such as Alpha, Delta, Lambda and others.  These variants are so labeled by WHO to simplify the naming process. Scientific names are still in use; however, this system allows the media and public to better understand the state of the global variants.

The Lambda Variant

The Lambda variant is the latest major variant being monitored globally and covered by the news media.  It is currently considered a variant of interest by the WHO, but many countries consider it at a higher level of variant of concern. Chile, Peru and Argentina are experiencing large-scale increases in SARS-CoV-2 cases driven by the Lambda variant.

Peru has been hit particularly hard with 81% of cases coming from the Lambda variant. In addition, Peru has the highest death rate according to Johns Hopkins (~600 deaths out of 100,000 cases). Currently, the Lambda variant has been detected in more than 28 countries globally.

The earliest detection of the Lambda variant was in November 2020 in Argentina. By December 2020, genomic surveillance put the Lambda variant at 0.5% of the infections in Lima, Peru. Then it rapidly took over the SARS-CoV-2 viral population: 20.5% in January, 36.4% in February, 79.2% in March, 96.6% in April 2021 and essentially 100% currently.

Although 60 – 70% of the target population in Peru have received two doses of vaccine, the primary product being used is CoronaVac. There are some issues with this vaccine.  In the laboratory, CoronaVac demonstrates little activity in antibody neutralization tests against the Lambda variant. This has unfortunately been born out clinically as it seemingly has little to no impact in preventing the spread of this variant. It may have some effectiveness in mortality prevention for the Lambda variant, but this has not been demonstrated by a study as of yet.

What does this imply for the United States and the Lambda Variant?

  1. The Lambda variant is not impacted by the vaccine used in most of Peru and Chile, so predictions cannot be made about what will happen in the United States based on their data.
  2. Because CoronaVac provides little to no protection against the Lambda variant, the dynamics of the epidemic in Peru and Chile are similar to an unvaccinated population.
  3. The Lambda variant has demonstrated that it can be very dangerous, particularly to unvaccinated individuals.
  4. Previous studies have demonstrated that there is very little protection provided to people who have had a natural infection from one variant when another variant comes along – unless they get an mRNA vaccine.
  5. There is slowly mounting evidence that people with a prior COVID infection, who then get an mRNA vaccine, have an even better immune response than those who just get fully vaccinated.
  6. The mRNA vaccines, including Pfizer and Moderna, are effective against the Lambda variant. Although serum from individuals who had either Pfizer or Moderna vaccines needed more antibodies to neutralize Lambda, they still had a more than sufficient antibody supply to neutralize the spike proteins.
  7. The Lambda variant likely has a higher infectivity rate than prior variants due to an L452Q mutation on the spike protein, in the “high-risk zone.”
  8. Outside of the laboratory, clinically and epidemiologically, the Lambda variant seems to be more easily and rapidly spread than some previous variants. It is perhaps more pathogenic as well.
  9. The Regeneron monoclonal antibody cocktail remains effective against the Lambda variant.
  10. Currently used tests for SARS-CoV-2 will work for the Lambda variant.
  11. The Lambda variant is a good example of why, even with vaccination, masks are still encouraged, as the vaccine while helpful in reducing mortality cannot offer 100% protection against all COVID variants or prevent spread.

The Future of the Pandemic

If the SARS-CoV-2 pandemic continues to play out like historical pandemics over the last 3,000 years – which it has so far – what can be expected?

First and foremost, the pandemic is a global event and will not resolve until it has been curtailed worldwide. Every country affects what happens globally. More variants will appear every few months in regions around the world that have high levels of infectivity and spread. Some will spread and eventually cover the globe. Others will remain local and be replaced by other variants.

Moreover, areas where many people take advantage of effective vaccines such as mRNA products will see decreased circulation of SARS-CoV-2 in their communities. This will be enhanced by the smart use of public health measures, such as face coverings and social distancing when they are needed. There will be occasional increases in viral cases even in these locations as long as the virus is circulating in surrounding communities at high levels.

However, areas where there is high vaccine resistance or hesitancy will continue to see larger numbers of cases and higher mortality. This will also be negatively affected by poor public health precautions and could cause super-spread events. All of these actions will have an impact locally, regionally and globally.

Stay safe and vaccinate.


A special thanks to Ruby Sahoo DO, MBA, FACP, SFHM, Hospital Medicine Performance Director, for her significant input.