BA.5, latest Omicron subvariant, is now dominant in U.S. and is expected to cause a new surge of infections if it hasn't already

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By Melissa Patrick

Kentucky Health News

As coronavirus cases continue to tick up in Kentucky, a new Omicron subvariant, reported to be the most transmissible yet, is now dominant in the U.S., and wastewater testing in Louisville confirms that it's the dominant strain there too. 

"Viruses are smart," Dr. Mark Burns, assistant professor of infectious diseases at the University of Louisville, told Sarah Ladd of the Courier Journal. "They know when they're being attacked and they do what they can to change whatever so they can survive."

July numbers from the Centers for Disease Control and Prevention show that Omicron's BA.5 subvariant now make up nearly 54% of the virus nationwide, the same as in Kentucky. Subvariant BA.4 now makes up nearly 17% nationwide and nearly 15% in Kentucky. 

And while the Omicron subvariants spread more quickly than other variants, "Data suggest that Omicron is less severe in general," says the CDC. However, the agency also cautions that a surge in cases may lead to significant increases in hospitalizations and death. 

Health experts have also expressed concern that the Omicron BA.5 subvariant will cause a new surge of infections in the U.S, even among those who are fully vaccinated or who have been recently infected. 

Subvariants BA.5 and BA.4 "are the most capable versions of the virus yet at evading immunity from previous infections and vaccines. Both variants have mutations in their spike proteins that are different enough from earlier versions of the virus that they are able to dodge some antibodies," Lauren Leatherby reports for The New York Times. Her article that looks at how BA.5 has affected other countries as a way to indicated what it could mean for the United States. 

Tina Reed of Axios explains it this way: "Studies show extra mutations in the spike protein make the strain three or four times more resistant to antibodies, though it doesn't appear to cause more serious illness." 

"BA.4/BA.5 certainly is more infectious compared to previous Omicron variants,” Yunlong Richard Cao, an immunologist at the Peking University in China, told Sanjay Mishra for National Geographic.

"Cao’s research shows that one of the most concerning traits of these variants is their ability to evade the immune system and break through herd immunity," Mishra reports. "That’s of particular concern because almost a quarter of the eligible U.S. population has not received a vaccine of any kind. And for those who have, even a full dose doesn’t seem to sufficiently block the new variants."

In other words, these two subvariants can evade protection from vaccines and previous infections better than most prior strains of the virus.

But that's no reason not to get vaccinated, say health experts, who continue to strongly encourage vaccinations and booster shots because they continue to offer protection against severe disease and death.

“Immunity from current vaccines is still expected to provide robust protection against severe disease, hospitalization, and death,” Dan Barouch, an immunologist at Harvard Medical School in Boston, told Mishra. 

"The virus is moving in a direction of escaping our vaccines more and more, but it has not found a way to escape the vaccines to a really significant degree," David Montefiori, a professor at the Human Vaccine Institute at Duke University Medical Center, told Aria Bendix of NBC News "For that reason, he added, people eligible for second boosters — those over 50 or the immunocompromised — may not want to wait," Bendix writes. 

A new vaccine that targets BA.45 and BA.5 is on the horizon. The Food and Drug Administration last week recommended modifying coming booster shots from Pfizer and Moderna to target them directly. The FDA said in a news release that the modified vaccines might be used starting in early to mid-fall. 

The FDA said its recommendation is for the primary vaccines to remain the same. "We have not advised manufacturers to change the vaccine for primary vaccination, since a primary series with the FDA-authorized and approved Covid-19 vaccines provides a base of protection against serious outcomes of Covid-19 caused by circulating strains of SARS-CoV-2," it said. 

All that said, National Geographic reports, "It’s unclear how the updated bivalent booster will fare against BA.4 and BA.5, since both the Moderna and Pfizer boosters generated a weaker antibody response to these subvariants than to BA.1." FDA "has admitted that the bivalent booster is 'already somewhat outdated.'"

Kentucky Health Commissioner Steven Stack, who is a physician, offered some advice in mid-June about who should consider waiting for a bivalent vaccine. 

"If you're over 60, if you are have multiple medical problems [and are] on medications, you should seriously consider going out and getting that fourth dose," Stack said. "Cases are rising and you want to keep your protection as high as you can. . . . Even if you're probably in your 50s, and you have no major medical problems, it's reasonable to talk with your personal physician if you would like and ask what their opinion is."

Stack encouraged everyone to get boosted this fall if they choose to wait, because once people move back indoors, we will need added protection against the virus. The CDC recommends a second booster for anyone 50 and older, as well as immunocompromised people 12 and older, at least four months after a first booster. 

In Kentucky, 61% of eligible residents, age 5 and older, have been fully vaccinated, and 57.9% of the state's entire population is, but only 45.5% of fully vaccinated people have been boosted, according to The Washington Post. 

To protect yourself and others from Covid-19, public-health advice remains the same: Get vaccinated and boosted, stay home if you are sick, get tested if you have symptoms, work to maintain good ventilation if entertaining indoors, consider pre-event Covid-19 rapid testing and wear an N-95 mask in indoor public places, especially if you are in a county with high transmission rates. 

Alex Sigal, a virologist at the Africa Health Research Institute and the University of KwaZulu-Natal in South Africa, told National Geographic: "We just have to be a bit careful in our daily life. Covid-19 is not done."