Interpretation of laboratory tests for prevention of the SARS-CoV-2 transmission

With the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), medical providers should take care to prevent the transmission of SARS-CoV-2 in hospitals including super-spreading. Understanding super-spreading would be useful to reduce future transmission. Some publications have shown clusters of SARS-CoV-2 such as at choir practice and in hospitals. Aerosol can be considered as a primary transmission route. As SARS-CoV-2 stability in aerosol is similar to SARS-CoV-1 with the higher reproductive number of SARS-CoV-2 than SARS-CoV-1, another factor causes rapidly spread-out, e.g. a higher discharge ratio from infected people or a higher viral intake ratio to human body. A basic research suggests higher infectivity of SARS-CoV-2 in the nose than the peripheral lung. Universal masking would be important to prevent the exposure of SARS-CoV-2 droplet to uninfected people. To detect SARS-CoV-2 infection, laboratory tests such as reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assays are applied. Although sensitivity and specificity are provided for the ability of the test, positive or negative prediction values are useful to indicate the possiblity of infection or non-infection in clinical practice. We have to realize that the positive and negative prediction values depend on the sensitivity, specificity, and infection probability of the patient.