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July 14, 2022
BY Ronda Wendler
The Omicron subvariants BA.4 and BA.5 are behind an increase in COVID-19 infections and hospitalizations. We spoke with MD Anderson’s Chief Infection Control Officer, Roy Chemaly, M.D., to learn about these new and highly contagious subvariants.
What exactly are the BA.4 and BA.5 Omicron subvariants?
They’re the most transmissible and immune-evasive strains of the COVID-19 virus to date. Today, they’re causing around 80% of COVID-19 cases in the U.S.
BA.5 is the more transmissible of the two and is causing 65% of cases, while BA.4 is causing 17%. They are subvariants of the coronavirus’s Omicron variant.
Variants and subvariants … what’s the difference?
Ever since it first emerged in 2019, the SARS-CoV-2 virus that causes COVID-19 has been shape-shifting, making slightly altered versions of itself. These new versions that keep appearing are called variants. Scientists identify them with Greek names, including Alpha, Beta, Gamma, Delta, and the latest variant – Omicron.
These variants, too, make new versions of themselves, called subvariants. BA.4 and BA.5 are the newest subvariants of the Omicron variant – the most dominant variant today.
What are the symptoms of the Omicron subvariants BA.4 and BA.5?
Based on what we’re seeing so far, the BA.4 and BA.5 subvariants are causing upper-respiratory symptoms, including:
This is further testament that vaccines are still effective at preventing severe disease. The current rise in hospitalizations may simply be attributed to the volume of infections in the community, not the severity of the disease.
Why are BA.4 and BA.5 so transmissible?
BA.4 and BA.5 are similar to earlier Omicron subvariants, but they have one important difference:  mutations in their spike proteins make it easier for them to penetrate human cells and cause infection.
These mutations can also help BA.4 and BA.5 escape disease-fighting antibodies created by past COVID-19 vaccines and prior infections.
This, along with the natural waning of vaccine protection and the fact that many communities are lifting COVID-19 restrictions, sets the stage for the virus to spread.
If BA.4 and BA.5 can dodge antibodies, do the COVID-19 vaccines still provide protection?
Even with the mutations in their spike proteins, these variants are still close enough to the original virus to respond to the COVID-19 vaccines. Your immune system may have a harder time identifying BA.4 and BA.5, but it will still red-flag these subvariants.
The current vaccines target the original virus, not the variants. So being vaccinated doesn’t offer as much protection as it once did against infection. But the vaccines do – and this is crucially important – prevent severe illness, hospitalization and death. If you become infected with the COVID-19 virus after being vaccinated, your symptoms are much more likely be mild.
What about updated vaccines that are in the works?
On June 30, the Food and Drug Administration (FDA) recommended modifying new booster shots for the fall to directly target BA.4 and BA.5.
Manufacturers are already designing and testing the new COVID-19 vaccines, and regulators have already planned how to fast-track the approval process. When they’ll be available is still up in the air, but mid-October to December is the goal.
Should those who haven’t gotten vaccinated or haven’t gotten boosted wait for the updated COVID-19 vaccines?
No. The risk for infection is currently very high, so don’t delay. If you’re eligible to get a vaccine or booster shot, do it now. Though it may not be a perfect match, the original vaccine will still protect you from severe illness.
If I get the current vaccine now, can I also get the updated one in the fall?
Yes, you can. The U.S. has pre-ordered 105 million of the updated shots, so there will be plenty to go around. If you get vaccinated today, you should still be eligible to get the variants-specific vaccine when it becomes available. You can have both vaccines.
In the meantime, what are our best defenses against BA.4 and BA.5?
The best way to stay safe from these subvariants is to follow the COVID-19 precautions that we know work, including:
Are there any extra precautions that cancer patients and other immunocompromised individuals should take to protect against BA.4 and BA.5?
The same precautions that benefit everyone apply to cancer patients. But I would add that, to protect people with cancer from COVID-19, it’s important that their family members, loved ones, and caregivers get vaccinated and follow the same recommended COVID-19 precautions.
Will the virus mutate again?
Yes. Viruses automatically reproduce by making carbon copies of themselves. But they aren’t perfect at it. Mistakes occur, resulting in a new version of the virus. If one of these mistakes works to the virus’ advantage and makes it easier for the virus to survive, then this new-and- improved version of the virus thrives while the older version dies.
Already, a new variant, BA.2.75 is emerging. It’s another super-contagious Omicron mutant. Whether it will outcompete BA.5 is yet to be determined. The World Health Organization has not yet named BA.2.75 a variant of concern, but virologists fear it could fuel a new wave of cases around the world. 
Any last thoughts about COVID-19?
We’re all pandemic-weary, but now is not the time to become complacent. The pandemic isn’t over, and these new subvariants are concerning. It’s likely that the COVID-19 virus, in whatever form, will be with us for some years to come.
Schedule your COVID-19 vaccine or booster at MD Anderson.
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We’re all pandemic-weary, but now is not the time to become complacent.
Roy Chemaly, M.D.
Chief Infection Control Officer
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