By Andria Borba

SAN FRANCISCO (KPIX 5) – With COVID-19 cases and the demand for testing skyrocketing amid the omicron surge, questions are being raised as to which of the two different types of tests available are the best to use in case of exposure.

The line to get tested for wrapped around the corner of 2nd and King Streets in San Francisco Tuesday afternoon. For Juliano and Renata Correia, it doesn’t matter what kind of test they get – they just need a test.

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“We are returning to Brazil tomorrow and we must be tested before going back,” Juliano Correia told KPIX 5.

The line outside a COVID-19 testing site in San Francisco during the omicron variant surge, January 4, 2022. (CBS)

The line outside a COVID-19 testing site in San Francisco during the omicron variant surge, January 4, 2022. (CBS)

With both rapid and PCR tests scarce during this post-holiday omicron surge, which do you need?

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“The appropriate tool in this pandemic to answer the question: ‘Do I need to isolate? Am I infectious and a risk to my neighbors?’ Is using a rapid antigen test because it only stays positive as long as you are infectious,” said Dr. Michael Mina, chief science officer of eMed.

Rapid tests only detect when you are infectious and shedding virus into the air. PCR tests are much more sensitive and can detect viral RNA for weeks after symptoms stop.

Dr. George Rutherford of UCSF said there is a best use case for PCR tests.

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“If you are older, if you have risk factors, if you think you might be a candidate for some of the antiviral drugs that are just coming available now or for monoclonal antibodies – you’ll definitely need a PCR diagnosis for that – because we will want to understand whether it’s omicron or delta all those kinds of things,” Rutherford told KPIX 5.