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We Know Kids
The Willows Pediatrics Blog

Office Covid-19 Testing: Rapid Antigen Test And PCR Test

Rapid Antigen Covid-19 Testing

Covid-19 SARS antigen test box
Willows Pediatrics
offers rapid COVID-19 testing. This is performed with the rapid lateral flow assay made by Quidel using Sofia 2 test kits. A sample is obtained from the lower part of your child’s nose using a nasal swab. We run the test in our office and parents receive results the same day. (However, if  a sample is obtained very late in the day, we may run your rapid antigen test shortly after the office opens the next morning. Swabs may be kept overnight and run the next morning).

There are a few limitations:

Covid-19 rapid in-office testing available at Willows Pediatrics

  • Rapid Covid-19 tests can give false negatives in asymptomatic individuals`because it may not detect low viral loads. For  asymptomatic individuals, the PCR test is the most accurate.
  • If your child is sick and the rapid Covid-19 test is negative, but symptoms increase or persist, we may recommend your child have a PCR test.
  • A rapid Covid-19 test and a PCR test done may be done at the same time. If the rapid test is negative your child should quarantine until results of the PCR are known.
  • Rapid antigen and PCR testing is available on Saturdays and Sundays during our regular office hours.

How accurate is the rapid Covid-19 test?

  • In symptomatic individuals, the rapid test detects over 80% of individuals with a Covid-19 infection. Studies show rapid Covid-19 tests have a sensitivity ranging from 84.0% – 97.6% compared to PCR testing. However, Covid-19 antigen levels in swabs collected 5-7 days after the onset of symptoms may drop below the limit of detection of the test.
  • In asymptomatic individuals, the rapid test may only detect a third of the positive cases compared to PCR testing.

More details on the accuracy of rapid COVID-19 tests is available here.

PCR Covid-19 Testing

Unlike the rapid test, which looks for bits of coronavirus proteins, or antigens, the PCR test is a molecular test that detects genetic material of the coronavirus. PCR tests detect ultra-low levels of viral RNA, which is why they are recommended for asymptomatic individuals who may not have enough viral load to be detected by the rapid test. PCR testing can also be done on people with symptoms.

If your child needs a PCR Covid-19 test, a sample is obtained from your child’s nose using a nasal swab. This swab is sent to Norwalk Hospital or Quest labs, and your child should quarantine until the results come back. The turn-around time for results is typically about 48 hours. Since we send the PCR test to an outside lab, we do not have control over when results are available. (Please note, for individuals who have a PCR test because of a Covid-19 exposure, a negative PCR does NOT mean they can shorten the recommended quarantine period.)

How accurate is the PCR Covid-19 test?

PCR tests have a sensitivity and specificity greater than 95%. This means the chances of a false negative or a false positive are less than 5%.

How does my child get tested?

Please call our office for an appointment. We test symptomatic and asymptomatic children of any age. The sample is obtained outside, either outside in your car for asymptomatic children, or outside our building (in a safe area) at the end of the visit for symptomatic children.


We submit the cost of the Rapid Covid-19 test to your insurance. When the PCR test is done, the outside lab submits the bill to your insurance.