Early COVID and Flu Testing Can Benefit You

Early COVID and Flu Testing Can Benefit You


With the ability to take PCR or antigen tests, many reasons exist to do so sooner than later.

September 29, 2022

One of the toughest questions to consider is which COVID test to get. This will depend on you and your situation, including a scenario like considering a test to ensure your child who doesn’t have symptoms can go to sports practice after hanging out with teammates who tested positive. 

“As new variants arise, they aren’t necessarily getting less dangerous. It’s just that more people have immunity due to vaccines, natural infections or a combination of the two. COVID has proven to be different from other viruses that become less dangerous,” said Allyson Kozak, Ph.D., MBA, NRCC, a scientific liaison at Roche Diagnostics. 

COVID-19 at-home rapid antigen tests are convenient and empower you to get quick results.


If there’s no room for doubt, other options exist. Have a professional clinician administer your rapid tests. Or, depending on the circumstances, ask for PCR rather than an antigen test.

Another situation you could face involves anyone with symptoms of cold, flu or COVID. They may need antiviral medications early to fight infection.

“A PCR test can be especially valuable at the beginning of an infection,” said Jamie Deeter, M.S., Ph.D., a scientific partner at Roche Diagnostic.

That’s because PCR tests can find evidence of disease in the earliest stages of infection when there’s only a small amount of virus in your body. Other tests may miss those early signs of disease. The same is true for PCR tests for the flu and other types of viruses. 


A Benefit of Testing Early


If you think you might have the flu or COVID, testing early can help you determine – and receive – the best course of treatment, including antiviral medications during the window when they can be most effective.

With antiviral medications, timing matters. “All antivirals work best within a few days of symptom onset,” Deeter said. “For COVID-19, the medication can be used within five days of symptom onset, though the majority of data lends itself to three days. While for the flu, antivirals work best within a 48-hour window.” 

What do those time frames have to do with testing? You have to move quickly if you want antivirals to work. You’ll need a prescription for antivirals – and, most likely, a visit to the doctor – whether you’re treating COVID-19 or flu. And to qualify for a prescription, you’ll need test results. 

“Since time is of the essence, if you’ve been exposed to a known positive, it might make the most sense to get a PCR test right away,” Deeter said. “You’d get accurate results faster than if you waited until symptoms began and then at-home testing.”


Which test is best:

Rapid antigen and PCR tests for COVID-19 and flu

Download Which Test is Best for You Chart

  Rapid Antigen PCR
Can I take it at home? Yes No, ask for it at your doctor's office, pharmacy or testing site
. When is it most accurate? When you have symptoms As early as before you have symptoms, and through symptoms
When is it least accurate? When you don't have symptoms Later in an infection (Because it detects small amounts of virus, you could keep testing positive for up to 90 days.)
How many times do I take it? Use multiple tests over a few days, especially if you don't have symptoms Once
When can I get results? 15 to 20 minutes (Flu tests take longer because you mail in a sample) 15 minutes to 24 hours (Rapid PCR tests turnaround in less time)
Can I use it for flu as well as COVID? Yes, but as of now, for flu the sample must go to a lab Yes, there's a combined test

Allyson Kozak, Ph.D., MBA, NRCC, is a board-certified clinical chemist and specializes in clinical chemistry, toxicology and immunoassays, including SARS-CoV-2 antibody diagnostics, at Roche Diagnostics. She has also served as a laboratory medical director, toxicology expert witness and assistant professor at Case Western Reserve University School of Medicine.


Jamie Phillips Deeter, M.S., Ph.D., obtained her doctorate in infectious diseases, specifically studying viral evolution related to coronaviruses. Previously she has been an ORISE fellow at the CDC and served as a director of research for a small biotech firm. She joined Roche’s medical and scientific affairs team in 2017. During the pandemic she helped launch three of Roche’s SARS-CoV-2 diagnostic tests and has served as a subject matter expert.

Disclaimer: This content is provided for educational and informational purposes only and does not constitute providing medical advice or professional services. The information provided should not be used for diagnosing or treating a health problem or disease, and those seeking personal medical advice should consult with a licensed physician. Always seek the advice of your doctor or another qualified health provider regarding a medical condition.