A variant of covid that spreads quickly is highly contagious and can cause advanced infections, but is not more serious or dangerous than previous strains, local experts say.
The omicron subvariant, known as BA.5, has “really taken off, nationally and locally,” said Dr. Lee Harrison, a professor of infectious disease and epidemiology at the University of Pittsburgh.
“It’s very, very infectious,” Harrison said. “There’s no doubt. As for immunity, it seems that even if you have had the previous variants of omicrons, there are enough differences in the BA.5 that you can reinfect yourself quite easily. ”
Nationally, the subvariant accounted for about 54 percent of the sequenced strains, according to data from the Centers for Disease Control and Prevention, Harrison said. The related BA.4 subvariant constituted about 17% of the sequenced strains.
“We’re seeing something very similar to national trends,” Harrison said. “In Allegheny County, we’ve seen a very rapid increase recently at BA.4 and BA.5, with BA.5 much more frequent.”
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CDC data for the week ending July 2 indicates that BA.4 and BA.5 accounted for about 59% of cases in the region, he said, and most of these were BA.5.
The new strain of covid is the latest in a series of variants and subvariants that have emerged since the start of the pandemic, said Dr. Amesh Adalja, a Pittsburgh-based infectious disease expert and senior researcher at Johns Hopkins. Center for Health Security.
This BA.5 subvariant is “very similar” to the BA.4 subvariant, he said, but “clearly different” from previous versions of the omicron variant.
As new subvariants have emerged, they have become more contagious, said Dr. Tom Walsh, an infectious disease specialist for Allegheny Health Network. Subvariant BA.5, Walsh explained, is “slightly more contagious and slightly more immunoevasive,” meaning it is more likely to cause advanced infections, or cases of covid-19 in fully vaccinated individuals.
The disease is now “approaching measles” in terms of how contagious it is, said BA.5.
Despite the contagious and evasive immune nature of the variant, experts said fully vaccinated individuals are still unsure of the worst outcomes.
“Vaccines are extremely effective in terms of preventing serious illness, hospitalization and death,” Adalja said.
Hospitalization figures “are rising slightly,” Harrison said, but death figures “remain relatively stable.”
“What has happened is that the nature of the people admitted to the hospital has changed with respect to the onset of the pandemic,” he said. “So if they’re hospitalized, they’re usually less severe than before. Hospitalizations increase, because we’re seeing a lot of infections. We still see very serious cases and we still see deaths, but compared to the onset of the pandemic, the severity at the hospital has become less severe. ”
Walsh said most people admitted to hospitals in the Allegheny health network with the virus are not vaccinated or are elderly people with multiple health problems.
Hospital and outpatient therapies that treat covid-19 remain effective against the latest subvariants, he said, and the same basic mitigation strategies that have been highlighted since the start of the pandemic may still reduce the risk of infection. .
Overall, Walsh said, omicron infections appear to cause “less serious disease” than previous variants.
Vaccine manufacturers are working to produce new vaccines that may be more effective against omicron and other variants, Walsh said. But creating a vaccine specifically targeted at the variant that is currently dominant can be tricky, he said, as variants change so quickly that a new variant could be taking control when the vaccine is ready to be administered.
The BA.5 subvariant will not be the latest new variant or subvariant of the coronavirus, Adalja said.
“BA.5 is the dominant strain of the virus right now. It will eventually be supplanted by something else,” he said. “There will be one after that and one after that as well. That’s what the virus will do: it will evolve so we can continue to infect ourselves.”
That’s why researchers are working on pan-coronavirus vaccines that target “all variants and subvariants” and provide immunity to constantly mutating strains of the virus, Walsh said.
It’s unclear when updated vaccines may be available, Walsh said, though some experts have already suggested this fall.
A new variant is already emerging abroad. Scientists say the variant, called BA.2.75, can spread quickly and prevent vaccine immunity and previous infection, according to The Associated Press. It is unclear whether it could cause more serious disease than other omicron variants, including BA.5, prominent worldwide.
Julia Felton is a staff writer for Tribune-Review. You can contact Julia at 724-226-7724, jfelton@triblive.com or via Twitter.