| Specimen no. | Amount | Purpose | Testing requirements | Collection schedule |
|---|---|---|---|---|
| S1 | 45 mL of blood (in adults) collected in 5-6 sodium citrate or sodium heparin tubes, enabling subsequent PBMC isolation Once isolated, PBMCs can be stored in 2-6 cryotubes (1.5-mL) at a concentration of 10-15 million cells per millilitre | To restimulate PBMCs and measure the Th1, Th2 and Th17 responses as well as cytokine expression and immune suppressors | PBMCs will be processed immediately and frozen at -80°C | Will be collected from all contacts during initial and final visits |
| S2 | 5 mL of blood collected in 1 serum separator tube Once separated by centrifugation, serum samples can be stored in 2 cryotubes (1.5-mL) | To measure IgG subclasses and gain information about antibody-mediated immunity and type of cell-mediated immunity | Serum samples will be centrifuged, aliquoted into a fresh tube and frozen at -80°C | Will be collected from all contacts during initial and final visits |
| S3 | 2 mL of blood using 1 green-top blood collection tube | To measure complete blood count and leukocyte count | Samples will be tested at a local hospital or frozen at -80°C | Will be collected from all contacts during initial and final visits |
| S4 | Nasopharyngeal swab in phosphate-buffered saline | To diagnose infection by means of PCR17 and to measure mucosal cytokine production | Before testing, the sample will be stored at 4°C to prevent nucleic acid and cytokine degradation; it will be tested as soon as possible If possible, PCR testing should take place at a clinical or public health laboratory to allow reporting of positive cases to public health authorities Nucleic acid remaining following PCR testing should be stored at -80°C Should specimen remain following PCR testing, the sample media will be split into 2 aliquots before being sent to the laboratory for measurement of cytokines | Will be collected from all contacts during initial and final visits; will be collected from symptomatic contacts during follow-up visit |
Note: PBMC = peripheral blood mononuclear cell, PCR = polymerase chain reaction.