Factors causing serological results to outnumber PCR -based testing results

l PCR-related–leading to underestimation of cases

○ Sample collection, transport, storage, and processing.

○ Reduced viral load in asymptomatic cases.

○ Focus of infection not always nasopharynx, in many cases lungs.

○ Population under -testing

l Serological

○ Immune response sensitive (when tested with confirmed cases) and specific (when tested on pre-COVID-19 sera).

○ The presence of antibodies indicates current or past exposure, whereas PCR testing may only indicate current infection.

○ The load threshold for antibody production may be much lower than that required for PCR testing to be positive.