Background: Nasopharyngeal (NP) specimens are commonly used for the detection of respiratory viruses, but throat and saliva specimens are easier to obtain. The objective of this study was to compare the viral yield of direct fluorescent antigen detection of NP specimens and nucleic acid amplification tests (NAT) of direct fluorescent antigen-negative NP specimens with the viral yield of NAT of throat swab and saliva specimens.
Methods: NP, throat swab, and saliva specimens were obtained from children and adolescents aged </=17 years. Direct fluorescent antigen testing of the NP specimen for respiratory syncytial virus, influenza A and B viruses, and parainfluenza virus was performed. If no virus was detected, NAT was performed for these 4 viruses, adenovirus, and human metapneumovirus. If a virus was detected by either method, NAT for the same virus was performed for the corresponding throat swab and saliva specimens.
Results: A virus was detected in 105 of the 137 NP specimens. The same virus was detectable by NAT in 87 (83%) of 105 throat swab specimens and 77 (74%) of 104 saliva specimens. The likelihood of viral detection among throat swab and saliva swab specimens was higher when the NP specimen tested positive by direct fluorescent antigen testing, compared with NAT alone, and when the specimens were obtained within 3 days after symptom onset, compared with later in the illness.
Conclusions: Throat swab and saliva specimens are inferior to NP specimens for the detection of respiratory viruses but might be acceptable for screening in a setting where it is impractical to obtain an NP specimen.