“…As we showed, conducting head-to-head comparisons of NPS and saliva for both PCR and antigen test is critical to dissect if matrix effects in saliva exist. As only few studies have assessed saliva in the context of SARS-CoV-2 antigen tests, and those that have, recorded variable results [ 35 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ], it can currently not be excluded that antigen tests generally show a reduced sensitivity across diverse tests systems. Alternatively, these effects may be test-dependent and can be modest enough to allow application in mass testing as a recent study suggests [ 41 ].…”