What is the difference between the lower nasal swab collection, as opposed to the deep nasopharyngeal swab? Is it less accurate?

A saliva or lower nasal swab is a preferred alternative to the invasive deep nasopharyngeal swab. With any test, there is the possibility of a false negative, and no COVID-19 test is 100% accurate. As long as the tests fall within acceptable limits, it is considered accurate. With PCR testing, it is the most accurate and sensitive test for COVID-19 detection available to date.