In this study, real-time RT-PCR was performed using the previously published primers M+25: AGA TGA GTC TTC TAA CCG AGG TCG and M-124: TGC AAA AAC ATC TTC AAG TCT CTG for quantification of viral load [28] . RNA extraction was done on each swab sample followed by PCR in duplicate or triplicate using 5 μL of RNA per each PCR reaction. Briefly, the Power SYBR Green RNA-to-CT 1-Step Kit (Applied Biosystem, Foster City, CA) was used with a 20 μL reaction mixture. For each PCR run, standards were designated for the plate and viral loads were calculated using fluorescence data acquired at the end of each annealing step. The amount of unknown sample was extrapolated based on the standard curve and was reported as viral copy number.