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What to Know About Omicron's Parade of Subvariants

Spikey, yellow models of the coronavirus on a red background.
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For the most up-to-date news and information about the coronavirus pandemic, visit the WHO and CDC websites.

What's happening

The omicron variant of COVID-19 keeps changing, creating newer, more contagious variants, dragging out the pandemic.

Why it matters

The more contagious omicron subvariants seem to be evading some immunity from prior infections with COVID-19 and are driving the current wave of cases.

What it means for you

People are still dying from COVID-19 every day, but the number of deaths is a fraction of what was seen last winter. Most people now have some protection against severe disease, thanks to vaccines, boosters and prior COVID-19 infection.

After rising sharply in May, the average daily number of COVID-19 cases is plateauing, but it's still hovering much higher than earlier this spring, according to data from the US Centers for Disease Control and Prevention. And the current COVID-19 impact varies depending on which area of the country you're in -- cases in some states in the Northeast and Midwest are declining, according to The New York Times, while states in the South and the West have higher community levels of COVID-19. 

Driving the current wave of cases (many of which are caught at home and not accounted for in official numbers) are newer versions or subvariants of omicron, the variant responsible for the record-breaking winter surge of COVID-19. BA.2, or "stealth omicron," was the first subvariant of omicron to cause an increase in contagiousness concerns, but BA.2.12.1 quickly took over as the dominant strain causing infections in the US, according to CDC data. 

Now scientists are watching how BA.4 and BA.5 grow and how they'll affect the current COVID-19 wave. They make up about 11.4% and 23.5% of COVID-19 cases, respectively, according to a CDC estimate. Like BA.2 and BA.2.12.1 (and BA.1.1 and BA.3), the two newer subvariants are still considered omicron -- the most contagious variant of concern to date, but one that typically causes less severe disease for the individual.

Much has changed in the COVID-19 pandemic since the early days of 2020. Every household is eligible for some at-home COVID-19 tests ordered through the mail for free, and children as young as 6 months are now eligible for a COVID-19 vaccine starting this week. As the pandemic and the virus causing it evolve, here's what we know about omicron's subvariants.  

What are the symptoms of the current omicron variants? How are BA.2, BA.4 and BA.5 different?

Data available currently suggests that BA.2 (and BA.2.12.1) doesn't cause more severe disease than the original omicron variant, even if it is more transmissible. (The World Health Organization notes that the transmission difference between original omicron and stealth omicron is smaller than the difference between delta and omicron.) 

While more research is needed on BA.4 and BA.5, they may be even more transmissible than earlier omicron subvariants, as newer variants need to have an advantage (like increased transmissibility) to overtake the previously dominant version. Dr. Eric Topol, a scientist and professor of molecular medicine at Scripps Research, suggested on Twitter that BA.4 and BA.5 may also carry an increased risk of COVID-19 reinfection.

There isn't information available now to suggest a difference in COVID-19 symptoms between different types of omicron. For many people who catch COVID-19 now (particularly those who are fully vaccinated and boosted), symptoms resemble cold symptoms such as sore throat, runny nose and fatigue. Back pain is a peculiar new symptom of COVID-19 that some people with omicron have reported, and the once-common "loss of taste or smell" appears to be much less common with omicron variants than with older strains.

If you have symptoms and are wondering whether it's COVID-19, taking a test and staying home while you're sick will help protect people more vulnerable to severe COVID-19 disease. 

Read more: Is It Allergies or COVID? How to Tell the Difference 

Omicron, variants and sublineages 

Variants are made up of multiple lineages and sublineages. Each variant has a "parent" lineage, according to the CDC, followed by other lineages, which you can think of like a family tree. As the virus spreads between people, mutations occur, but not all of them change the characteristics of the virus in meaningful ways. 

The omicron variant and its sublineages made the virus much more contagious and capable of infecting more people, but it's led to less severe disease, on average, than the delta variant

Genomic surveillance can detect variants and sublineages. Scientists in South Africa were able to quickly identify omicron as a new variant because of the way it presents through PCR tests. The original omicron causes a dropped signal or marker on the test that sets it apart from delta, which was the dominant variant prior to omicron. BA.2, however, doesn't have the same signal, called an S gene target failure. This makes it more stealthy, though genomic sequencing (which happens to about 10% of COVID-19 PCR tests in the US) will detect all omicron subvariants and coronavirus variants in general.

However, detecting new variants or subvariants may be becoming more difficult as the number of sequences shared across the world have "dropped precipitously," Dr. Maria Van Kerkhove, an infectious disease specialist with the WHO, said last week. While the impact was still enormous, having real-world data available quickly after scientists detected omicron was a benefit during the worldwide surge last winter. 

A face mask and two syringes on a neon-pink background.
Sarah Tew/CNET

Are the new variants more contagious? Will the COVID treatments still work?

The WHO, considering all available real-world data, concluded that there's no reported difference in severity between omicron BA.1 and BA.2, despite the latter's growth advantage. 

Between BA.2 and BA.2.12.1, the newer version is believed to be about 25% more transmissible, CDC Director Dr. Rochelle Walensky said at a media briefing in late April. 

What about BA.4 and BA.5? More research and information is needed to see how they'll impact the pandemic, but there's reason to believe both subvariants are more contagious given their growth in the US the last few weeks. 

Like the original omicron, BA.2 means more fully vaccinated people will experience breakthrough infections. But those who are fully vaccinated, and especially boosted against COVID-19, "continue to have strong protection against severe disease," Walensky said at the April briefing.   

Paxlovid, an effective antiviral medication, is still being prescribed to treat COVID-19 in people at high risk of severe disease in the current variant landscape. One monoclonal antibody therapy, bebtelovimab from Eli Lilly, is still authorized to treat COVID-19 caused by the omicron variants. 

As the variants that cause COVID-19 evolve and change, however, the FDA may take back its authorization of certain treatments if research shows they're no longer effective. 

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.