The equipment and supplies needed for processing the specimens will differ based on specimen type and existing capacity and needs of the laboratory. Regardless of the specimen type, each laboratory should have a dedicated space where the site laboratory technician can store supplies and perform processing. There are key considerations for each laboratory (Box 1). Refer to Specimen Collection Module for more details on laboratory assessments.

Generally, the local laboratory will receive specimen collection and processing supplies from the central laboratory (in the situation with both a local and central laboratory). The site laboratory technician and site coordinator should perform an inventory of the supplies received and report any concerns to the central laboratory team. Some items may need to be purchased locally, where possible. If space allows, the field collection supplies should be organized in a way that allows the survey laboratory technician to easily gather supplies on the day of specimen collection; this storage location may either be in the local laboratory or another designated space at the site. Supplies needed for processing should be organized in the designated location where processing will be conducted [See Specimen Processing SOP and Supplies List].

There are three primary laboratory technicians involved in a serosurvey, each with specific roles and responsibilities.

^a Based at the central or national laboratory where testing is conducted.

Figure 2. Laboratory Roles and Responsibilities

At the end of each day of specimen collection the Site Laboratory Technician should receive the specimens from the survey team. If DBS are being used, this may be every few days.

Below are considerations for processing whole blood to serum for IgG antibody detection by EIA

• Whole blood should be received in a sterile tube labeled with participant ID number.
• To isolate serum:
  • Whole blood should be allowed to clot after collection (for ~1 hour) and then centrifuged at 1000 × gravitational units (g) for 10 minutes to separate the serum.
    • If specimens will be centrifuged in the community prior to transport the Site Laboratory Technician should check all specimens upon receipt to confirm serum has separated; if not, centrifuge again.
  • Remove serum with a fine-bore pipette and transfer to a cryovial labelled with key details about the specimen (e.g., participant ID, date of collection, specimen type)
  • At the time of processing it is recommended to observe and record additional details about the specimen, such as signs of hemolysis and estimated specimen volume (Figure 3).
  • After aliquoting, serum can be stored at 4−8°C for up to 7 days before testing. If kept for longer periods, serum should be frozen at -20°C or lower. Serum should not be thawed once frozen until intended for biomarker testing. Repeated freezing and thawing should be avoided to preserve quality of antibodies.
  • Store labelled cryovials in cryoboxes and record relevant details in a laboratory register and freezer box map (see below section on Documentation). If there are multiple aliquots for specimens, store each aliquot in separate boxes so that they may be shipped separately (done to ensure backup specimens are available in case of issues during shipment).
    • Prior to survey start, develop a standard method for organizing specimens within the cryobox.

Figure 3. Processing of whole blood specimens

Click on photos to expand.

Figure 4. Examples of hemolysis, ranging from mild (light pink) to moderate and severe.

Dried blood spots (DBS) on filter paper cards (e.g. Whatman 903 Protein Saver filter cards) can be used to collect blood specimens. Below are considerations for handling dried blood specimens (DBS) specimens after collection.

• Following collection, the survey laboratory technician should place each DBS specimen in an individually labeled re-sealable plastic bag with a desiccant to avoid contamination.
• Upon receipt at the local laboratory the site laboratory technician should remove each card from its bag and allow the specimen to air day for 1-4 hours at room temperature (20-25°C). Where possible this should be done in a dust-free area, such as inside a fume hood, to minimize exposure to contaminants during drying. Note: procedures may vary depending on the DBS device selected [link to references for handling 903 cards].
• At the time of drying, it is recommended to observe and record additional details about the specimen, such as number of spots and size/quality.
• After DBS specimens have dried, return to labelled plastic bag with desiccant and store in a cool place at the local laboratory.
• Temperature: If room temperature is above 25 °C then DBS specimens can be placed in the refrigerator. Always transition specimens from warmer to colder temperatures (e.g., room temperature to 4 °C to -20 °C). Moving a specimen from a colder temperature to a warmer temperature may expose specimen to moisture.
• Humidity: Specimen quality may be impacted by humidity. If humidity is a concern, store DBS specimens in an airtight container with additional desiccants. Use a humidity monitor placed near the specimen to track daily fluctuations in humidity.
• Further processing of the specimen (elution to obtain serum specimen) typically occurs at the time of testing. Refer to Assay Protocols module for more details.