Nylon flocked swabs have higher viral DNA concentration and adhere better to epithelial cells than rayon swabs. They are more sensitive to nasopharyngeal aspirate than rayon swabs. Similarly, flocked swabs are less expensive than rayon swabs. In addition to their cost, rayon swabs are more environmentally friendly than flocked nylon ones. Their flocked fibers absorb a lot of liquid. Check https://www.allswabs.com/medical-swabs/rayon/.