Test negative with home test, but still show symptoms?

AUSTIN (KXAN) — New confirmed COVID-19 cases are the highest they’ve been since January in Texas. One in four Central Texans who get tested are testing positive, and those numbers don’t include all of those testing at home.

Several viewers replied to a KXAN inquiry, asking if anyone had tested negative with an at-home test, only to test positive with a PCR test shortly after.

Curative, a testing company with 26 sites in the Austin area, says those initial negative at-home tests are not coming back negative because they’re less effective with the latest variant, but because they’re just less accurate, but widely available now .

“Lots of individuals receiving those free at-home tests over the last handful of weeks just creates that greater access to the at-home antigen test,” Jamil Sabbagh with Curative explained Wednesday.

Generally, at-home tests are about 85% accurate, while PCR tests are about 98% accurate, meaning PCR tests catch 98% of actual infections that they test for.

“Academic studies actually showed that PCR tests are typically more accurate in detecting COVID-19 infections compared to other testing options like the at-home antigen tests. And anecdotally, antigen tests actually clearly label that their option is not as accurate as the gold standard,” Sabbagh explained.

This week, Austin Public Health said the COVID-19 vaccines and boosters seem to be less effective with this latest variant, which could partially explain the uptick in the community spread in our area.

“We don’t have as much protection from natural immunity, as we’ve seen with previous variants of COVID-19,” Dr. Desmar Walkes said Tuesday.

But, because more people are now vaccinated, the severity of this most recent variant has remained relatively low.

Hospitalizations used to be a key indicator of community spread of the virus, but with this latest variant, that’s changed. APH is trying to get that word out ahead of the Fourth of July weekend, when plenty will be gathering.

“While hospitalizations have remained low, compared to previous surges, community transmission is quite high. This is not consistent with public awareness,” Janis Bookout told commissioners Tuesday.

If you start showing COVID symptoms this weekend but test negative with an at-home test, CDC guidance says there’s still a chance you have the virus. You’re asked to test again within the next 24-48 hours, or simply go get the PCR test.

So, what’s the difference between the two tests? Here’s what Curative had to say:

“Our primary testing method is that PCR test, which actually stands for polymerase chain reaction. To kind of just break it down in layman’s terms, basically, as you collect a sample, you heat it up, cool it down multiple times over an extended period of time in a laboratory. What that does is actually break down the DNA and actually allows it to replicate, if it does replicate enough times, hitting a specific threshold shows you that an individual is either a positive for COVID-19 or be negative for COVID-19. The antigen test is a little bit different. It’s actually typically a 15 minute test, actually putting this extraction buffer on the sample itself. So very similar to a pregnancy test. And it just, you know, works a little bit a little bit faster, and focuses on the actual molecules themselves, rather than the DNA of the molecules,” Sabbagh said.

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