A call to a swab is a term used in the medical field to refer to a swab test. A swab test is a procedure in which a sample of cells or fluids is taken from a patient's body and tested for the presence of a particular virus or bacteria. The swab is usually taken from the nose, throat, or other areas of the body. AVAST is an antivirus software company that provides protection against malicious software, viruses, and other online threats.