Common Covid-19 Tests in US

 PCR vs Antigen 

Test	Approach	Accuracy
PCR Test	A molecular test—searches for the virus’s genetic material in a nasal swab or saliva sample, and it is often processed in a highly complex laboratory	Tests run in lab: highly accurate Tests run in boxlike analyzers: less accurate
Antigen Test	Search the sample for viral proteins instead of the virus’s genetic code, are gradually becoming more widespread in the U.S.	Considered less precise than PCR tests Considered most accurate when used in the early-symptoms stage

Cost / Turnaround Time

Test	Cost	Turnaround Time
PCR Test	If you have symptoms or have had contact with someone infected, typically free Otherwise, could be $60 to $300 (if not covered by insurance)	Offered at a drive-through location, a doctor’s office, a pharmacy such as CVS or Walgreens or a lab Time: Boxlike analyzers: 15 to 45 mins Offsite lab: > 2 days
Antigen Test	If you have symptoms or have had contact with someone infected, typically free Otherwise, could be $25 to $100 (if not covered by insurance)	Offered at doctor’s offices, nursing homes and other congregate settings where groups of people need testing fast. Time: Typically 15 mins

Which test hurts the least?

“If it doesn’t hurt, they’re not doing it right,” said Frank Peacock, associate chair of the department of emergency medicine at Baylor College of Medicine, of the deeper nasal swabs.

Collection Method	Ranking of Pain Level
Spitting into a container	Least
Cheek swabs	Moderate
Nasal swabs	Moderate
Deeper nose swabs	Most

Caution with Results

A test represents only a snapshot of a moment in time. Depending on the test you get and how the sample is collected, you may receive a false negative or false positive result due to:

• Sample collection or test errors
• Test collected too early 
• Some people may seek a test before a detectable amount of virus has built up, which could produce a negative result even if they are infected. 
• Test collected too late
• Tests can pick up the genetic material of the virus and produce a positive result when patients are no longer infectious.

References

1. Covid-19 Tests: Answers on Cost, Accuracy and Turnaround Time
2. Saliva viral load is a dynamic unifying correlate of COVID-19 severity and mortality
• A new research at Yale found that saliva viral load to be a better predictor of disease than nasopharyngeal viral load.
3. Chinese cities using anal swabs to screen COVID-19 infections
• Stool tests may be more effective than respiratory tests in identifying COVID-19 infections in children and infants since they carry a higher viral load in their stool than adults, researchers at the Chinese University of Hong Kong (CUHK) had said in a paper published last year.