As of now, there is no consensus about whether or not tears can accurately detect the virus in an infected person, but early study results have shown a lower amount of the virus in tears than in other bodily fluids. Some researchers believe parts of the virus might be able to spread from a person's nasal cavity into their eyes, and eventually into tears in the inner corner of the eyes. Whether or not this type of testing will work is still uncertain as scientists have been testing many bodily fluids like semen, saliva, urine, and tears to determine whether or not the virus can be detected in them and if it can, how much.

Humans produce tears in the back of their eye sockets, which is close to the nasal cavity where most COVID-19 tests are being done now. The nasal cavity is located at the back of the nose and is where the COVID-19 virus starts reproducing in people exposed to the virus.

Nasal swab tests are designed to collect samples from the nasal cavity that have some genetic material of the virus (DNA and RNA). Tear tests for COVID-19 would try to focus on this similar area of the head as there is a small, thin layer of tissue called the 'conjuctiva' that acts as a bridge between the nasal cavity and the eye socket.

There is a growing number of research studies as well as media reports about COVID-19 tests that use samples of tears, instead of nasal swabs, throat swabs, saliva collection, blood draws, or other bodily samples. Tears originate near the nasal cavity, and someone with COVID-19 can shed viral particles in their tears.

Like nasal swab tests, COVID-19 tests using tears analyze the sample through polymerise chain reaction (PCR) and are currently proposed as a potential option for diagnostic testing (checking whether someone has an active infection), which is different from antibody testing (checking whether someone had a past infection and now has antibodies against COVID-19). It is important to note that COVID-19 tests using tears are still in the research and development phase.

Beyond the COVID-19 tests using tears that are being developed, Yale University has developed a COVID-19 diagnostic test that uses saliva collected in sterile containers, called SalivaDirect. On August 15, 2020, the U.S. Food and Drug Administration (FDA) issued an emergency use authorization for SalivaDirect, although more studies are in progress to better understand how well this test works.

The interest in COVID-19 tests using tears and saliva may be related to general interest in increasing the availability, accuracy, affordability, safety, speed, and ease of COVID-19 testing. For example, there is some interest in nasal swab test alternatives to reduce physical discomfort and to avoid inducing sneezing or coughing reflexes that could transmit virus particles to health care workers.