Expert discusses best time to use a COVID-19 home test kit

Dr. John Wherry suggests if you're using the home test as a precaution ahead of a gathering, test 6-12 hours before the event.
MAPLE SHADE, New Jersey (WPVI) -- With Christmas just days away, many people are excited to have a more normal holiday compared to last year.

"Last year was more isolated. We're seeing more people this year," said Roz Fleishman of Maple Shade, N.J.

But experts warn, even vaccinated people can contract and transmit COVID-19, so many public health officials urge testing before gathering.

New Jersey officials say they've recorded their highest new case total yet with more than 15,000 COVID-19 cases.

As a result, many in the area have made it an obligation to get tested before traveling.

Outside the CVS pharmacy on Kings Highway in Cherry Hill, a sign was displayed Thursday that said, "We do not have any at-home COVID tests at this time."

"CVS, Shop Rite, Walgreens, Walmart, everybody's out of them," said Frankie DeRosa of Maple Shade, N.J.

The City of Philadelphia canceled its rapid test kit distribution Thursday, announcing all 24,000 kits had already been distributed.

The pre-holiday city distribution resulted in long lines for the tests, which keep selling out at pharmacies.

It was a home COVID-19 test that led to a positive case detected among the holiday photo staff at the Moorestown Mall.

Photos with Santa were canceled or rescheduled Wednesday after an employee reportedly tested positive Tuesday.

The Burlington County Health Department launched an investigation after being notified Wednesday.

A VIP holiday photo spokesperson says the company is now in the process of notifying about 650 families who came into contact with this employee from December 17-21.

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In Delaware County, Pennsylvania, lines for COVID testing were long at the Haverford Area YMCA.



In Delaware County, Pennsylvania, lines for COVID testing were long at the Haverford Area YMCA.

Those there said while the wait was well worth it, they had no choice but to wait.

"There are no appointments. We looked all day yesterday for appointments, and there's none anywhere," said Alex Pearson of Merion Station.

In Philadelphia, at the CVS in Fairmount, it was more of the same.

"I looked online, and there was only one day available. I was working. Now, I'm out of luck," said Matt Kubiak of Center City.

Dr. John Wherry, director of the University of Pennsylvania's Institute of Immunology, suggests if you're using the home test as a precaution ahead of a gathering, test 6-12 hours before the event.

"That's going to make sure that when you're with other people you're at a low risk for transmitting," he said.

Wherry says antigen tests are generally very accurate and best used when you're most contagious.

But adds they may not pick up on the earliest stage of infection.

"So they pick up sort of the middle window of the infection," said Wherry. "They're going to miss the first, maybe one to two days you've been exposed."

Wherry says if you have COVID and you're testing to see if you're still positive-- a PCR test is best because antigen tests can also miss the end stage of infection.

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