Inexpensive, versatile and open-source methods for SARS-CoV-2 detection

ABSTRACT

Re-opening of communities in the midst of the ongoing COVID-19 pandemic has ignited a second wave of infections in many places around the world. Mitigating the risk of reopening will require widespread SARS-CoV-2 testing, which would be greatly facilitated by simple, rapid, and inexpensive testing methods. To this end, we evaluated several protocols for RNA extraction and RT-qPCR that are simpler and less expensive than prevailing methods. First, we show that isopropanol precipitation provides an effective means of RNA extraction from nasopharyngeal (NP) swab samples. Second, we evaluate direct addition of NP swab samples to RT-qPCR reactions without an RNA extraction step. We describe a simple, inexpensive swab collection solution suitable for direct addition, which we validate using contrived swab samples. Third, we describe an open-source master mix for RT-qPCR and show that it permits detection of viral RNA in NP swab samples. Lastly, we show that an end-point fluorescence measurement provides an accurate diagnostic readout without requiring a qPCR thermocycler. Adoption of these simple, inexpensive methods has the potential to significantly reduce the time and expense of COVID-19 testing.