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1. What is the difference between PCR tests and rapid antigen tests?

PCR tests have been the most commonly used diagnostic tool for COVID-19 up to this point. They require skilled laboratory personnel to collect, process, and analyze the sample, and the results can be available in hours to days. Rapid antigen test results are available in as little as 15 minutes and can be done in any setting.  Antigen tests work very well as a diagnostic test for people who are symptomatic or have been exposed to COVID-19 and also to screen asymptomatic people in school settings. PCR tests may also be used in these instances, but they may continue to give a positive result after someone has stopped being infectious. 

2. When should I test for Covid-19?

You should seek a COVID-19 test when you are exhibiting symptoms of COVID and if possible, within the five days following a known close contact with someone who has been diagnosed with COVID.  

3. If my antigen test is negative, should I take another test?

If you are exhibiting symptoms, you should take another antigen test 24-48 hours later or get a PCR test. You should follow isolation guidance until you receive the results of the second antigen test or the PCR test.  

If you do not have a known exposure and are not exhibiting symptoms, there is no need to seek another test.

4. Should I get a PCR test if I have a positive antigen test?

A positive antigen test does not need to be confirmed with a PCR test. Rapid antigen tests have low rates of false positives so a person who tests positive on a rapid antigen test almost certainly has COVID-19.  

You should follow isolation guidance and notify your close contacts. In the near future, you will be able to alert your contacts of a positive at-home test via an anonymous link using MassNotify. Currently, this feature is only available for positive results from official PCR tests, where the link is provided by Massachusetts DPH

5. I have heard that with Omicron, there is less virus in the nose and more in the throat. Should I swab my throat and use that for an antigen test?

No, you should not swab your throat. The antigen tests are validated for use with nasal swabs, so you should continue to swab your nose as instructed. 

6. Do I need to provide a PCR test to return to work or school?

The Massachusetts Department of Public Health (MDPH) is discouraging employers, schools, and other settings from requiring a PCR test for anyone returning from isolation or quarantine. PCR tests can continue to give positives after someone has stopped being infectious. 

Additionally, the Department of Public Health’s protocols do not require a return to work or school letter for anyone returning from isolation or quarantine and this requirement is discouraged. Needham Board of Health nor the Massachusetts Department of Health provide these letters. If required, employees should contact their health care provider.

7. Do I need to report my home antigen test to Needham Public Health?

You may report a positive home antigen test results to Needham Public Health via this Google Form. This is for case tracking purposes for Needham Public Health and to help provide you with the isolation guidance. Due to the case numbers, Needham Public Health is unable to follow up with you regarding your test result. Please visit mass.gov/isol8 to view the full state isolation and quarantine guidance.