The collection of nasopharyngeal specimens for this study followed guidance from the National Influenza Research Laboratory, HPA, Colindale, London, and the manufacturer of the POCT. A good specimen for the detection of influenza or RSV must contain a substantial number of respiratory epithelial cells, which are mainly obtained from the nasal swab. A throat swab alone will contain mainly squamous epithelial cells in which influenza does not replicate. In brief, collection of routine nasopharyngeal swabs was as follows:
a single swab with cotton wool bud is inserted in one nostril and rubbed against and above the nasal turbinates
a second swab is used to abrade the tonsils and pharynx
place both swabs in the same bijou bottle of virus transport medium
break off the swab sticks (scissors may be used)
screw lid tightly on to the bottle.
Trial-specific procedures were as follows.
‘Near-patient diagnostic group’ (QuickVue Influenza A + B test) and Deferred QuickVue test
The sterile sponge tipped swab provided in the QuickVue Influenza A + B test was inserted into the nostril that presented the most secretions under visual inspection, according to manufacturer’s instructions.
Using gentle rotation, the swab was gently pushed until resistance was met at the level of the turbinates (< 1 inch into the nostril). The swab was rotated a few times against the nasal wall.
Specimens collected from patients in the ‘near-patient diagnostic group’ were tested immediately for the presence of Influenza A and B according to the manufacturer’s instructions.
An identical specimen was collected from patients randomised to the molecular diagnostic group and conventional virus culture group. These specimens were collected into virus transport medium and were refrigerated at 4 °C until they were transported at the earliest opportunity by the hospital transport system to the microbiology laboratory. They were processed upon receipt during normal working hours by the QuickVue A + B test.
Deferred QuickVUE influenza A + B test, prompt and deferred molecular testing, and conventional virus culture
We collected nasal and pharyngeal swabs for molecular and conventional virus culture studies using the opposite nostril to that used for the ‘near-patient’ and ‘deferred’ QuickVue Influenza A + B tests.
Using gentle rotation, a dry swab with cotton wool bud was inserted into the nostril and rubbed against and above the nasal turbinates.
A second swab is used to abrade the tonsils and pharynx.
The swab tips from both swabs were placed into a single bijou bottle of virus transport medium, agitated and then cut off, or broken off, into the medium.
These specimens were refrigerated at 4 °C until they were transported to the Microbiology Laboratory at the earliest opportunity by the hospital transport system.
Specimens from subjects randomised to the ‘prompt’ molecular diagnostic group were processed upon receipt during normal working hours. Specimens for ‘deferred’ molecular diagnostic testing from subjects who were randomised to the ‘conventional’ diagnostic group were stored at ‒20 °C
Specimens from subjects randomised to the ‘prompt’ and ‘conventional’ diagnostic groups were processed upon receipt during normal working hours by conventional virus isolation tests.
