Abstract
BackgroundWe evaluated the feasibility of asking pregnant women to self-collect and ship respiratory specimens.MethodsIn a preliminary laboratory study, we compared the RT-PCR cycle threshold (CT) values of influenza A and B viruses incubated at 4 storage temperatures (from 4 to 35°C) for 6 time periods (8, 24, 48, 72, and 168 hours and 30 days), resulting in 24 conditions that were compared to an aliquot tested after standard freezing (−20°C) (baseline condition). In a subsequent pilot study, during January–February, 2014, we delivered respiratory specimen collection kits to 53 pregnant women with a medically attended acute respiratory illness using three delivery methods.ResultsCT values were stable after storage at temperatures <27°C for up to 72 hours for influenza A viruses and 48 hours for influenza B viruses. Of 53 women who received kits during the pilot, 89% collected and shipped nasal swabs as requested. However, 30% (14/47) of the women took over 2 days to collect and ship their specimen. The human control gene, ribonuclease P (RNase P), was detected in 100% of nasal swab specimens. However, the mean CT values for RNase P (26·5, 95% confidence interval [CI] = 26·0–27·1) and for the 8 influenza A virus positives in our pilot (32·2, 95% CI = 28·9–35·5) were significantly higher than the CTs observed in our 2010–2012 study using staff-collected nasal pharyngeal swabs (P-values < 0·01).DiscussionSelf-collection of respiratory specimens is a promising research method, but further research is needed to quantify the sensitivity and specificity of the approach.
Highlights
We evaluated the feasibility of asking pregnant women to self-collect and ship respiratory specimens
Encouraged by the results of several studies that examined self-collected respiratory specimens,[4,5,6,7,8,9] we conducted a follow-up study in 2013–2014 to explore the feasibility of forgoing household visits by asking pregnant women with acute respiratory illness (ARI) to self-collect and ship nasal swabs
Encouraged by findings from our laboratory experiment which suggested influenza viruses would remain stable during a reverse transcription PCR (rRT-PCR) cycle threshold
Summary
At the study reference laboratory (Marshfield Clinic Research Foundation laboratory in Marshfield, Wisconsin), four influenza isolates from specimens originally collected in 2012–2013. The rRT-PCR cycle threshold (CT) values indicate when fluorescence generated in the reaction significantly exceeds background and are inversely proportional to the amount of nucleic acid target that is present in the specimen.[11,12] CT values for detection of each virus and RNase P were compared with the baseline CT. Participants were given written instructions and directed to view an online video (Appendix S1), which demonstrated how to collect a respiratory specimen using a mid-turbinate nasal swab, place the swab in a tube containing M4-RT transport medium, and ship the specimen along with a signed consent form using the packaging provided (without freezing or cold packs). Study procedures were reviewed and approved by the KPNC and Abt Associates institutional review boards
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