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UCSF doctor says improper testing practices, changes in COVID variant leading to spread of BA.5

SAN JOSE, Calif. (KGO) — Why is the BA.5 COVID-19 variant spreading so quickly? A UCSF infectious disease expert now says he’s testing — not bad behavior — that could be behind the disease’s rapid spread.

As the country continues to battle the latest dominant variant of COVID-19 BA.5, President Joe Biden has said vaccinations, treatment and testing are essential.

But what happens when one of these strategies doesn’t work as expected?

Isaac Velasquez of San Jose says he and his fiancée never tested positive on their home test, despite being exposed and showing symptoms of COVID.

RELATED: People Who Never Got COVID Even After Being Exposed Share Their Stories

“I ended up testing negative twice. She tested negative four times,” Velasquez said. “It didn’t quite add up, so we decided to go to the hospital to do some of the PCR tests. We ended up testing positive a few days later.”

This story is becoming mainstream according to UCSF infectious disease specialist Dr. Peter Chin-Hong, and it is causing concern.

“I’m afraid there’s a lot of transmission,” Chin-Hong said. “Not because people are sneaky or irresponsible, they just don’t know they’re positive.”

Chin-Hong said it’s not that the tests don’t work, it’s that the BA.5 variant just behaves differently than other strains of the virus.

He says symptoms of BA.5 first appear in the throat, which means a nasal test won’t give a positive result for several days.

“You can dab your nose until there’s no tomorrow, but if all the action is in your throat, it takes a while for this virus to get up to your nose,” said said Chin-Hong. “That’s why you go negative for a long time until you go positive when the virus gets on your nose.”

RELATED: Doctors Explain 5 Reasons Omicron’s BA.5 Will Be ‘Worst’ Subvariant Yet

Chin-Hong said the other factor is how a vaccinated person’s immune system reacts to this strain.

You may have symptoms, but there are not enough virus particles in your body for the tests to show positive results.

“Rapid tests need 100,000 or more viruses to come back positive, whereas a PCR only needs five or less than 10 viruses to come back positive,” Chin-Hong said.

For this reason, he suggests a PCR test may be better than a rapid test, or use the swab from the home test to swab your throat and then your nose for a better result.

Chin-Hong also said testing at least five days after symptoms start could help prevent this highly transmissible variant from spreading even further.


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