This is an international, multicentre, non-interventional, observational study to assess the clinical diagnostic performance of a rapid, point of care (POC) COVID-19 (SARS-CoV-2) antigen In vitro diagnostic (IVD), The KnowNow SARS-CoV-2 Rapid Antigen Test, using saliva samples when compared to reverse transcription polymerase chain reaction (RT-PCR) as the standard detection of COVID-19 infection.

The KnowNow SARS-CoV-2 Rapid Antigen Test which uses saliva and is a lateral flow diagnostic device that can detect the SARS-CoV-2 specific Antigens that are present on the surface of the virus. The KnowNow test is an affordable, user friendly, and point of care device that can be mass produced as part of a multipronged strategy to address the global COVID-19 pandemic.

A saliva sample is collected from someone with suspected COVID-19 and mixed with a running buffer. The mixture is added to the sample pad of the KnowNow test, from where it migrates through the lateral flow strip. If COVID-19 Antigens are present, they bind to capture proteins on a test line and are made visible by secondary reagents within the device. The test result is visually assessed after 15-30 minutes and provides a binary positive (two lines) or negative (one line) result. Levels of COVID-19 Antigen differ dependent on disease progression. A visible test line (marked T) indicates the presence of COVID-19 Antigen in sufficient quantity in the collected sample to be detected. The appearance of the control line (marked C) confirms that the test has been performed correctly.

Inclusion Criteria:

1. Male or female aged 18 years or over (or age of adult consent in some states within the United States).
2. Suspected COVID-19 infection and / or presenting with at least 1 recognised symptom Fever or chills. ie: Cough. Shortness of breath or difficulty breathing, fatigue, muscle or body aches, headache, new loss of taste or smell, sore throat
3. Be willing and able to comply with study procedures.
4. Be able to give written informed consent.

Exclusion Criteria:

1. Inability to give written informed consent.
2. Vaccinated against SARS-CoV-2
3. Adults unable to undertake the requirements of the nasopharyngeal or saliva sample collection for physical or psychological reasons
4. Subjects with other significant disease, condition, or at the Clinician's discretion.

Male or female aged 18 years or over (or age of adult consent in some states within the United States) with suspected COVID -19 infection.