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The Delta strain of the SARS-CoV-2 virus was first identified in India at the end of 2020. Since then, other variants have reached the headlines in one place after another. Yet, Delta has maintained its dominance on top of the COVID-19 variants chart for much of 2021.

While the healthcare community has been busy fighting Delta, we also have an eye on what is next? As SARS-CoV-2 continues to mutate, there is no limit to the number of new variants. The real question is: when and where will the next deadly variant popup be? Will we be ready for it?

Why is Delta the dominant strain?

  • More contagious. According to the latest research, Delta has the most transmissibility of any variant so far. It is more than 2x [i] more transmissible than previous variants.
  • More severe. Studies [ii] from both, Scotland and Canada, show that hospitalization was more likely for patients infected with Delta than other variants.

Understanding the why and how of these factors is helping scientists identify the next “deltas”.

The next three

Recently, three SARS-CoV-2 variants have emerged, causing interest among scientists: Mu, Lambda, and C.1.2. They each show increased transmissibility and resistance to vaccine boosted defenses. Compared to Delta, these three are not posing as much threat yet, but they share similar traits. Let’s take a close look at each one.

Mu Variant (B.1.621)

The Mu variant was first discovered in January 2021 in Columbia. [iii] Since then, it has spread to at least 43 countries. On August 30, Mu was classified as a variant of interest by WHO (World Health Organization). In that same week’s update, WHO described Mu as having “potential properties of immune escape.” [iv] Specifically, the Mu variant can elude antibodies at levels like the Beta variant.

So far, even though the Mu variant has a worldwide footprint, its prevalence has been limited to less than 0.1% globally. In South America, the Mu variant has a firmer grasp on the COVID-19 caseload consisting of 13% of cases in Ecuador and 39% in Columbia. In the US, it makes up less than 0.2% of recent COVID-19 infections. [v]

Lambda Variant (C.37)

Identified in Peru in December 2020, this variant makes up 64% of Peru’s COVID-19 infections but less than 0.5% of worldwide cases [vi] despite its presence in at least 40 countries. [vii] During its peak in late June, WHO gave Lambda the “variant of interest” label as it accounted for about 12% of South America’s new infections at that time. Since then, it has receded to less than 3% of that continent’s new cases. Lambda is troubling in that it carries several spike protein mutations that, when compared to the original SARS-CoV-19 strain, make it more infectious and more resistant to antibodies from prior infections and vaccines. [viii] In another study, the mRNA vaccines, Pfizer and Moderna, do maintain a similar rate of efficacy against the Lambda variant as with the original virus. This study also found monoclonal antibody treatments to have the same effectiveness. [ix]

C.1.2 Variant

C.1.2 first appeared in South Africa in May 2021. It quickly accounted for 1.6% of the country’s cases in June and then 2% in July. [x] Since then, C.1.2 has declined in South Africa but spread to 10 more countries. C.1.2 is catching many researchers’ attention. Labeled by WHO as Alerts for Further Monitoring. South African scientists have found in C.1.2 many mutations in common with some variants of concern like Delta and Beta. Of even more concern are the antibody-evading mutations found in C.1.2 that are not found yet in other variants. [xi] More research is needed to identify how effective current vaccines are against C.1.2 infections.

How to stay ready?

A proactive approach is the best way to keep ahead of new SARS-CoV-2 variants. So far, mRNA vaccines are the most effective for preventing and reducing the severity of infections. In the clinical setting, proper personal protective equipment (PPE) and strict adherence to infection control procedures can assist in controlling the intra-facility spread. Beyond that, as surges in COVID-19 cases ebb, take advantage of these breaks to re-evaluate your response effectiveness during the last surge to better identify needs and opportunities.

Partner with us

At AB Med, we want to be your community healthcare partners. We have been at the forefront of fighting the pandemic, supporting facilities and communities just like yours. We have the experience, skills, personnel, and resources to help you improve your COVID-19 response. We are in this together, Let’s Connect.


  1. CDC (2020). Coronavirus Disease 2019 (COVID-19). [online] Centers for Disease Control and Prevention. Available at: https://www.cdc.gov/coronavirus/2019-ncov/variants/delta-variant.html.
  1. CDC (2020). Coronavirus Disease 2019 (COVID-19). [online] Centers for Disease Control and Prevention. Available at: https://www.cdc.gov/coronavirus/2019-ncov/variants/delta-variant.html.
  1. outbreak.info. (n.d.).outbreak.info. [online] Available at:https://outbreak.info/situation-reports/mu?loc=COL&loc=GBR&selected=COL [Accessed 16 Sep. 2021].
  1. www.who.int. (n.d.). Weekly epidemiological update on COVID-19 – 31 August 2021. [online] Available at: https://www.who.int/publications/m/item/weekly-epidemiological-update-on-covid-19—31-august-2021.‌
  1. www.who.int. (n.d.). Weekly epidemiological update on COVID-19 – 31 August 2021. [online] Available at: https://www.who.int/publications/m/item/weekly-epidemiological-update-on-covid-19—31-august-2021.
  1. outbreak.info. (n.d.).outbreak.info. [online] Available at: https://outbreak.info/situation-reports/lambda?loc=PER&selected=PER [Accessed 16 Sep. 2021].
  1. www.who.int. (n.d.).COVID-19 Virtual Press conference transcript – 4 August 2021. [online] Available at: https://www.who.int/publications/m/item/covid-19-virtual-press-conference-transcript—4-august-2021 [Accessed 16 Sep. 2021].
  1. SARS-CoV-2 Lambda variant exhibits higher infectivity and immune resistance – 28 July 2021. Available at: https://www.biorxiv.org/.
  1. SARS-CoV-2 Lambda Variant Remains Susceptible to Neutralization by mRNA Vaccine-elicited Antibodies and Convalescent Serum (03 July 2021). [online] . Available at: https://www.biorxiv.org/content/10.1101/2021.07.02.450959v1.full.
  1. outbreak.info. (n.d.).outbreak.info. [online] Available at: https://outbreak.info/situation-reports?pango=C.1.2&loc=ZAF&selected=ZAF  [Accessed 16 Sep. 2021].
  1. The continuous evolution of SARS-CoV-2 in South Africa: a new lineage with rapid accumulation of mutations of concern and global detection – 24 August 2021. Available at: https://www.medrxiv.org/ .

By: Erik McLaughlin MD, MPH and Aikaterini Papadopoulou, B.Arch


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Erik Mclaughlin
Erik McLaughlin MD, MPH
Chief Medical Officer
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