One of the most challenging aspects of the COVID-19 pandemic has been testing for the virus. 

There are a two main types of possible COVID-19 testing:

1. Molecular tests: Molecular tests look for evidence of genetic material from the virus. These types of tests are completed using either a nasal swab, a throat swab, or another bodily fluid like saliva. Molecular tests are more sensitive than antigen tests, (meaning that they are more accurate at correctly identifying patients with the disease), but less specific than antigen tests (meaning they are less accurate at correctly identifying patients without the disease). Types of molecular tests include polymerase chain reaction (PCR) tests, viral RNA tests, and nucleic acid tests. The main type of molecular COAVID-19 test is a PCR test. 
2. Antigen tests: Antigen tests use nasal or throat swabs to look for proteins (antigens) from the virus. These tests are rapid, and results are available in as little as 10 minutes. Antigen tests are also less expensive than others, and use simpler technology than PCR tests. 

Molecular (PCR) tests at official testing sites can be difficult to obtain due to limited availability, packed facilities, and wait times. As a result, at-home testing has become more popular. There are some at-home PCR tests that can be dropped off or mailed into a laboratory for processing.

However, questions have come up about how effective most at-home tests are that focus on anterior nasal swabbing (just inside the nostrils) are compared to other following testing methods:

1. Nasopharynx (the back of the nasal cavity) 
2. Oropharynx testing (throat)
3. Saliva

Nasopharyngeal swabs are the main testing method for detecting respiratory pathogens, including COVID-19. This type of testing is only done by health professionals and can be very uncomfortable for patients. This method is not recommended for self-testing because they can be incorrectly done and cause pain or other problems. Medical histories should also be taken in a healthcare facility in case patients have a deviated septum or are more prone to nosebleeds or similar contraindications.

Nasopharyngeal swabs have been shown to have higher sensitivity (accuracy of identifying patients with a disease) than other testing types such as anterior nasal swabs and throat swabs. Throat swabs have been found to have have lower sensitivity than all other test types listed above: nasopharyngeal swabs, anterior nasal swabs, and saliva tests. 

Oropharyngeal tests (throat swabs) should also only be completed by health professionals due to similar risks of potential harm when done at-home by patients including piercing the back of the throat when pushed too hard, gagging, or swabbing in incorrect locations. In addition, the swab shouldn't punch the tongue, cheeks, gums, or teeth, which can be difficult for patients to see on their own.

Saliva tests are done by having the patient spit into a tube. Unlike nasopharyngeal tests or oropharyngeal tests, saliva tests can be done at home and dropped off or mailed in for testing by a lab. 

A recent study in the peer-reviewed scientific journal The Lancet found that nasal swabs had higher sensitivity than throat swabs in lab testing, meaning nasal swabs are less likely to give false negative results. Preprint data also shows that saliva tests could provide better information on a person’s potential disease outcome because the amount of viral load in saliva is associated with how severe a disease is or might be.

Most at-home tests are done with nasal swabs because nasopharyngeal swabs and throat swabs are not recommended for at home and saliva tests need to be sent to a lab for processing. 

Throat swabs are not as commonly used for COVID-19 testing because 1) current data shows they have lower sensitivity than nasopharyngeal swabs, nasal swabs, and saliva tests, and 2) because throat swabs shouldn’t be done and at home which makes it less convenient and less scalable than anterior nasal swabs.

In the peak of the circulation of the Omicron variant at the end of 2021 and beginning of 2022, there was discussion among experts and the public about whether it was worth it to swab the throat in addition to the nasal cavity for common at home anterior nasal tests. Some initial data showed that swabbing the throat before swabbing the inside of the nose produced more sensitive results for the Omicron variant. 

However, the data is conflicting, and health authorities such as the U.S. Food and Drug Administration advice against it because of potential risks of doing an at-home throat swab, and because the data isn’t clear.