New Covid subvariants are highly contagious, immune-evading, experts say



A fast-spreading variant of Covid is highly contagious and can cause breakthrough infections, but it’s no more serious or dangerous than previous strains, local experts say.

The Omicron subvariant — known as BA.5 — has “really declined nationally and locally,” said Dr. Lee Harrison, Professor of Infectious Diseases and Epidemiology at the University of Pittsburgh.

“It’s very, very contagious,” Harrison said. “There’s no doubt about that. In terms of immunity, it looks like even if you had the previous omicron variants, there are enough differences in the BA.5 that you can reinfect yourself fairly easily.”

According to data from the Centers for Disease Control and Prevention, the subvariant made up about 54% of strains sequenced nationwide, Harrison said. The related BA.4 subvariant accounted for approximately 17% of the strains sequenced.

“We’re seeing something very similar to national trends,” Harrison said. “In Allegheny County, we’ve seen a very rapid increase in BA.4 and BA.5 recently, with BA.5 being much more common.”


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CDC data for the week ended July 2 shows that BA.4 and BA.5 made up about 59% of cases in the region, he said, and the majority of those BA.5.

The new Covid strain is the latest in a series of variants and subvariants that have emerged since the pandemic began, said Dr. Amesh Adalja, a Pittsburgh-based infectious disease expert and senior scientist at the Johns Hopkins Center for Health Security.

This BA.5 subvariant is “very similar,” he said, to the BA.4 subvariant, but “distinctly different” from previous versions of the Omicron variant.

As new subvariants have emerged, they have become more contagious, said Dr. Tom Walsh, infectious disease specialist at Allegheny Health Network. The BA.5 subvariant, Walsh explained, is “a little more contagious and a little more immune-avoidable,” meaning it’s more likely to cause breakthrough infections — or cases of Covid-19 in fully vaccinated individuals.

The disease is “now approaching measles” in terms of its contagiousness, he said of BA.5.

Despite the variant’s contagious and immune-preventable nature, experts said fully vaccinated individuals are likely still safe from the worst of the consequences.

“The vaccines are extremely effective in preventing serious illnesses, hospitalizations and deaths,” Adalja said.

The number of hospital admissions “is rising slightly,” Harrison said, but the number of deaths “remains relatively flat.”

“What has happened is that the type of people who are being hospitalized has changed from earlier in the pandemic,” he said. “So when they do get hospitalized, they tend to be less severe than they used to be. Hospital admissions are increasing because we are seeing a large number of infections. We’re still seeing very severe cases and we’re still seeing deaths, but compared to earlier in the pandemic, hospital severity has shifted to less severe.”

Most people admitted to Allegheny Health Network hospitals with the virus are either unvaccinated or elderly with multiple health conditions, Walsh said.

Inpatient and outpatient therapeutics used to treat Covid-19 are still effective against the latest subvariants, he said, and the same basic mitigation strategies that have been emphasized since the pandemic began could still reduce the risk of infection.

In general, Walsh said, Omicron infections appear to cause “less severe disease” than previous variants.

Vaccine makers are working to create new vaccines that may be more effective against Omicron and other variants, Walsh said. But developing a vaccine that specifically targets the currently dominant variant can be difficult, he said, because variants change so rapidly that a new variant could take over when the vaccine is ready to be administered.

Subvariant BA.5 will not be the last new variant or subvariant of the coronavirus, Adalja said.

“BA.5 is currently the dominant strain of the virus. It will eventually be replaced by something else,” he said. “There will be one after this and one after that. That’s what the virus will do – it will evolve to keep infecting us.”

That’s why researchers are working on pan-coronavirus vaccines that would target “all variants and subvariants” and provide immunity to ever-evolving strains of the virus, Walsh said.

It’s unclear when updated vaccinations might be available, Walsh said, although some experts have suggested as early as this fall.

A new variant is already appearing overseas. Scientists say the variant – dubbed BA.2.75 – may be able to spread quickly and bypass immunity to vaccines and previous infections, according to The Associated Press. It’s unclear if it could cause more serious diseases than other Omicron variants, including the world-renowned BA.5.

Julia Felton is a Contributor to the Tribune Review. You can contact Julia at 724-226-7724, [email protected] or via Twitter .

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