Guide to the COVID-19 Variants

A Guide to the COVID-19 Variants: What You Need to Know About Testing and More

Multiple SARS-CoV-2 variants have emerged since the start of the pandemic, and experts, including the CDC Director Dr. Rochelle Walensky, have spoken about the urgency to vaccinate as many people as possible before more contagious variants of the virus can spread widely.

The race against the variants is underway. Here’s what you need to know about them:

What is a variant?

Like all viruses, SARS-CoV-2 (the virus that causes COVID-19), is constantly mutating as it moves through the population, causing new variants to emerge. Variants contain changes (mutations) in the virus’ RNA.  Most of these variants are inconsequential from a clinical perspective, though they’re useful for tracking the spread of the virus through the global population.

How does the virus mutate?

Coronaviruses, like SARS-CoV-2, are known for crown-like spikes on their surfaces called spike protein, which is how the virus attaches to and infects host cells. Some mutations in the spike protein do have the potential to increase the ability of the virus to spread or cause more severe illness. Additionally, these mutations can allow the virus to evade protective antibodies induced by previous infection and/or vaccination and detection by testing methods. These are the variants that scientists are avidly tracking.

Which variants with clinical implications are widely circulating?

A U.S. government interagency group has established three classifications for the SARS-CoV-2 variants it is monitoring: Variant of Interest, Variant of Concern, and Variant of High Consequence. There are currently no observed variants in the third, most severe category, but there are five in the Variant of Concern category. Here is what scientists and public health officials know about each one:

  • B.1.1.7 (Alpha, commonly known as the UK Variant): First observed around London and southeast England amid a surge of cases last fall, this variant was first detected in the US in December 2020 and continues to spread quickly here. It’s thought to be 50% more transmissible than the original strain and more likely to cause severe illness. The CDC has confirmed that the B.1.1.7 variant is now the dominant strain in the US, but the great news is that vaccines are highly effective against it.
  • B.1.351 (Beta, commonly known as the South African Variant): This variant is also thought to be 50% more transmissible than the original strain, though it’s unknown whether it causes more severe disease. Current vaccines appear to be less effective against this variant; in South Africa, where the variant emerged, the government decided to stop the rollout of the AstraZeneca vaccine after a study demonstrated that the vaccine was less effective against it.
  • P.1 (Gamma, commonly known as the Brazil Variant): Believed to be more transmissible, this variant is responsible for the deadly second wave that’s currently gripping Brazil. It also seems to have taken hold in Canada. This variant is thought to more easily re-infect people who have recovered from COVID-19 and send younger people to hospital. The efficacy of the current vaccines against this variant has not yet been determined.
  • B.1.427 / B.1.429 (Epsilon, commonly known as the California Variants): Two variants that originated in California are thought to be 20% more transmissible than earlier strains of SARS-CoV-2. It’s unclear whether they cause more severe disease, but vaccines are likely to work well against them.
  • B.1.617.2 (Delta, commonly known as the India Variants): The B.1.617.2 variant is the only variant on this list that is categorized as a Variant of Interest. It is behind a series of surges in India and has become the leading variant in many states in India. 

The CDC has established a national genomic surveillance program to identify new and emerging SARS-CoV-2 variants in the US.  For up-to-date information check out the COVID Data Tracker (

How do the variants respond to diagnostic testing?

The great news is that to date no mutation has curbed the accuracy of Labcorp’s PCR tests that identify active COVID-19. That’s because our tests target the nucleocapsid protein of the virus, which is less prone to mutations as it must be faithfully copied from generation to generation for the virus to survive.

Because our tests target the SARS-CoV-2 nucleocapsid, which is relatively well conserved across variants, our PCR tests can detect a SARS-CoV-2 infection due to the currently known variants. The sensitivity of our PCR test is not impacted by the variants. If you need to get tested, you can order a Pixel by Labcorp home collection kit here or talk to your doctor.

Labcorp continues to monitor the performance of all SARS-CoV-2 tests that we offer against newly emerging viral variants.

Is the U.S. testing for variants?

Continued genomic sequencing of the SARS-CoV-2 virus in new cases will provide a far more accurate picture of how variants are spreading and enable public health officials to respond effectively. Labcorp is proud to be working with the CDC on this effort. Because our labs receive thousands of samples from many states, we are uniquely positioned to catalog SARS-CoV-2 variants. These efforts provide the CDC information to inform national and state public health actions aimed at ending the pandemic.

The federal government is also taking steps to accelerate this important work; specifically, the recent stimulus bill directs $1.75 billion to the CDC to support genomic sequencing and surveillance initiatives. You can find estimates on the prevalence of the most common variants in the US here.