I keep hearing all these new terms since the omicron variant came on the scene-can you clarify what all these words mean?

COVID Variants

A: Yes! Here are some explanations of many of the buzzwords flying 🦟 around right now….variant of concern, neutralizing antibodies, immune evasion and more!

*Variant*: A variant is a version of the SARS-CoV-2 virus that has changes to its genetic sequence (i.e., mutations). These changes make it distinct from the other versions of the virus that have been circulating. Mutations occur when viruses replicate-so changes to the virus are expected. Not all changes are bad news, and not every new variant will be of concern. The World Health Organization (WHO) tracks new variants that emerge. They chose to name new variants after letters of the Greek alphabet. The latest variant identified was assigned the Greek letter omicron.

*Variant of concern*: A version of the SARS-CoV-2 virus is classified as ‘of concern’ because mutations may cause a) increased transmissibility (i.e., make it easier for the virus to spread from infected people to others), b) more severe illness, and/or c) tests, treatments or vaccines to not work as well. The omicron variant was classified as a variant of concern on November 26, 2021. The delta variant was classified as a variant of concern on May 11, 2021. For more info about the specific reasons why each variant was classified as ‘of concern’, see link here.

*Neutralizing antibodies*: Neutralizing antibodies attach to viruses and prevent the virus from attaching itself to and entering our cells. This is called neutralization. SARS-CoV-2 enters our cells by attaching the spike protein on its surface to the ACE2 receptor on the surface of our cells. When antibodies made by our body attach to the spike protein, the spike protein can’t attach to the ACE2 receptor. If the SARS-CoV-2 virus can’t attach to the ACE2 receptor, it can’t enter our cells. If it can’t enter our cells, it can’t infect us. If it can’t infect us, we don’t get COVID-19.

*Virus neutralization assay*: This is a lab test that provides information about how well antibodies are able to neutralize the SARS-CoV-2 virus. The SARS-CoV-2 virus is mixed with blood samples from people that received the COVID-19 vaccine and/or were previously infected with SARS-CoV-2. Scientists then look at how well antibodies in blood are able to “neutralize” the virus. So far, there is some preliminary evidence that neutralization of the omicron variant is decreased in those who received two doses of the Pfizer vaccine, compared to the original SARS-CoV-2 virus. Neutralizing activity of antibodies was strong, however, among people who received two doses AND were previously infected (this is called hybrid immunity) or among people who had received three doses.

*Immune evasion*: Immune evasion refers to the ability of viruses to avoid getting detected by antibodies that were produced by our body after getting vaccinated or infected. For a new variant to evade our immune system completely, mutations to the spike protein would have to be SO drastic that our antibodies no longer recognize it and thus no longer attach to it. While the omicron variant has numerous mutations (including on the spike protein), and early studies indicate that neutralizing activity is reduced in some groups (as noted above), it does not completely evade detection by our antibodies-phew!

Those Nerdy Girls will keep pushing out explanations of the latest new terms as the omicron variant situation evolves-check back in this space!

For more helpful omicron-related vocab explainers, check out this link from NPRs Goats and Soda (one of Those Nerdy Girls’ go-to trusted sources of COVID-19 information!)

For more information on the criteria for classifying variants, see here.

Our recent posts on omicron variant:


THIS JUST IN: Preliminary Omicron neutralizing antibody study

For more on viral neutralization assays, see here.

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