Comparison of Nasal and Nasopharyngeal Swabs for Influenza Detection in Adults

1Epidemiology Research Center, Marshfield Clinic Research Foundation, Marshfield WI, USA.
Clinical Medicine &amp Research 06/2012; 10(4). DOI: 10.3121/cmr.2012.1084
Source: PubMed


Examine differences in the detection of influenza by specimen and test type using paired nasal and nasopharyngeal swabs.DesignProspective studySettingEnrollment took place between January and March of 2007 in a central Wisconsin population.ParticipantsAdult patients were screened and enrolled by trained research coordinators following medical encounters for acute respiratory illnesses of <10 days duration.Methods
Paired nasal and NP swabs were collected from consenting patients and tested by both real time reverse transcriptase polymerase chain reaction (rRT-PCR) and viral culture. A composite measure of positivity was used as the gold standard; cases included any positive result by rRT-PCR or viral culture from either specimen type.ResultsPaired samples were collected from 240 adults; 33 (14%) individuals tested positive for influenza by rRT-PCR. Using rRT-PCR, the sensitivity of the nasal swab was 89% (95% CI 78 - 99%) and the sensitivity of the nasopharyngeal swab was 94% (95% CI 87 - 100%), compared to a composite gold standard.Conclusion
Test sensitivity did not vary significantly by swab type when using a highly sensitive molecular diagnostic test, but power was limited to detect modest differences.

Download full-text


Available from: David K Shay,
1 Follower
14 Reads
  • Source
    • "Using nasal swabs can therefore facilitate increased participation in active surveillance studies to detect novel influenza viruses. When PCR is used for viral detection, nasal swabs are comparable in sensitivity to nasopharyngeal swabs (Irving et al., 2012; Sung et al., 2008). Previous work has examined the impact of storage temperature and time on viral recovery from nasal swabs (Fereidouni et al., 2012). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Surveillance of healthy individuals at high risk for zoonotic influenza A transmission is important for tracking trends in influenza A epidemiology. Practical measurement methods that maximize viral recovery and produce low variability are essential when low viral loads are expected. For this study, lysing both a nasal swab and its storage medium was compared to lysing the storage medium alone to determine which method results in greater influenza A virus recovery. Independent results from two laboratories suggest that including the swab in the lysis step does not lead to higher influenza A virus recovery, and that recovery is less variable when only the swab storage medium is extracted. These results indicate that simply lysing the swab storage medium is an effective extraction method for nasal swabs collected during studies of influenza A virus exposure among healthy populations. Copyright © 2015. Published by Elsevier B.V.
    Journal of Virological Methods 02/2015; 217. DOI:10.1016/j.jviromet.2015.01.008 · 1.78 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The recently developed test-negative design is now standard for observational studies of influenza vaccine effectiveness (VE). It is unclear how influenza test misclassification biases test-negative VE estimates relative to VE estimates from traditional cohort or case-control studies. We simulated populations whose members may develop acute respiratory illness (ARI) due to influenza and to non-influenza pathogens. In these simulations, vaccination reduces the risk of influenza but not of non-influenza ARI. Influenza test sensitivity and specificity, risks of influenza and non-influenza ARI, and VE were varied across the simulations. In each simulation, we estimated influenza VE using a cohort design, a case-control design, and a test-negative design. In the absence of influenza test misclassification, all three designs accurately estimated influenza VE. In the presence of misclassification, all three designs underestimated VE. Bias in VE estimates was slightly greater in the test-negative design than in cohort or case-control designs. Assuming the use of highly sensitive and specific reverse-transcriptase polymerase chain reaction tests for influenza, bias in the test-negative studies was trivial across a wide range of realistic values for VE. Although influenza test misclassification causes more bias in test-negative studies than in traditional cohort or case-control studies, the difference is trivial for realistic combinations of attack rates, test sensitivity/specificity, and VE. Copyright © 2015. Published by Elsevier Ltd.
    Vaccine 02/2015; 33(11). DOI:10.1016/j.vaccine.2015.01.069 · 3.62 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We evaluated the added value of collecting both nasal and oropharyngeal swabs compared to nasal swabs alone for detection of common respiratory viruses by reverse-transcription polymerase chain reaction in hospitalized children aged <10 years. Nasal swabs had equal or greater sensitivity than oropharyngeal swabs for detection of respiratory syncytial virus, adenovirus, human metapneumoviruses, rhinovirus, and influenza viruses, but not parainfluenza viruses. The addition of an oropharyngeal swab compared to nasal swab alone increased detection of each respiratory virus by <10% in children aged <10 years. Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.
    The Journal of Infectious Diseases 05/2015; DOI:10.1093/infdis/jiv265 · 6.00 Impact Factor
Show more