When the SARS-CoV-2 virus enters the body, it invades human cells and reproduces. As the virus replicates, genetic changes can occur through mutations, altering the structure of the virus and causing variants.1,2 These variants can also acquire specific mutations of their own labeled as subvariants.
Sometimes these mutations leave the genetic material too broken to copy, and that virus doesn’t survive. Other times, these mutations can happen in a section of code that allows the virus to survive, and in the process, changes the virus. Mutations can allow the virus to spread more easily, or sometimes cause more severe symptoms.2
What are the SARS-CoV-2 variants of concern?
The scientific community tracks variants and subvariants and closely monitors the impact they might have on infection rates and disease severity. Certain SARs-CoV-2 variants are more transmissible than others and have spread swiftly worldwide. Those that significantly increase transmission of the virus or disease severity, and/or potentially reduce the impact of preventative or treatment measures are labelled Variants of Concern (VOCs).3 Global health authorities have different classifications for variants/subvariants to help prioritise monitoring and research, which ultimately helps informs the ongoing response to the pandemic.
Since the start of the pandemic only five variants have been classified as VOCs by the World Health Organization because of these increased risks to global public health.4 Omicron is the currently circulating VOC, which has taken off globally and produced numerous subvariants, including BA.1, BA.2 and BA.5, all of which have been globally dominant at some point in the past.5
What is the typical lifespan of a COVID-19 variant?
Variants exhibit a natural ebb and flow where new subvariants are emerging while older ones are diminishing. These cycles occur as the virus mutates, and when advantageous mutations develop, certain subvariants may survive and escape protection provided by vaccines, therapies or previous infection.6
As quickly as variants and subvariants have emerged, up to this point most Omicron subvariants have circulated for around eight months.5 When a subvariant has become dominant globally or in a specific region, that dominance lasts on average less than four months.5
SARS-CoV-2 has not spread uniformly across the world or on the same timetable. Many variants and subvariants exist regionally with some causing COVID-19 waves while others have limited impact. Of those that have spread globally, like Omicron, there are differences in its infection rates by location.5 There is also a difference in how quickly a subvariant will “take off.” Some variants become dominant quite quickly, like BA.1 or BA.2, while others spread at a slower rate, like BA.4, and may not ever become dominant.5 As the virus continues to mutate, the COVID-19 landscape remains dynamic and difficult to predict.
The Ebb and flow of Omicron subvariants
This graph depicts Omicron subvariants that have emerged and diminished from December 2021 to August 2022. These data are based on representative testing samples from the GSAID COVID CG database and show a period of dominance (over 50% of samples) for BA.1, BA.2 and BA.5 that changes over time. These samples are not indicative of total case counts.
Will more variants emerge?
The one thing we do know about the COVID-19 pandemic is that it is unpredictable, including when and where new variants will emerge, what their impact may be and how long they might be around. Therefore, it remains important to protect as many people as possible to prevent future infection, including immunocompromised individuals who are at high risk of severe disease and death.7
