This study describes the use of pooled screening strategies to detect early community transmission of COVID-19.
COVID-19 has shown us the importance of robust diagnostic testing. Given the limited testing capacity available in the US, people symptoms, but without travel or exposure history, were not tested. We do not have an accurate picture of the community circulation of the virus prior to the identification of individuals with positive results.
Sample pooling, a strategy used for community monitoring of other infectious diseases such as trachoma, might be deployed. Researches gathered all nasopharyngeal and bronchoalveolar lavage samples collected from Jan 1- Feb26, from inpatients and outpatients who had negative results by routine respiratory virus testing. Nine or 10 individual samples were pooled, and screening was performed using RT-PCR. Positive pools were deconvoluted and individual samples tested for confirmation.
A total of 292 pools were screened, consisting of 2740 nasopharyngeal samples and 148 bronchoalveolar lavage samples. The positivity rate for COVID was 0.07%. They found that the positive results were from nasopharyngeal samples collected from Feb 21-23.