- It can be kept at – 16 ℃ for a long time;
Clinical samples for the diagnosis and surveillance of measles and rubella should be obtained at the first contact between the patient with the clinical case and the health care system, irrespective of the stage of disease at which the patient presents. Depending on the country, blood obtained by venipuncture, dried capillary bloodspots on filter paper and/or oral fluid may be used.
Blood collection for serum by venipuncture and handling
Blood should be collected in a sterile tube (5 ml for older children and adults and 1 ml for infants and younger children) and labelled with the patient’s name and/or identification number and the collection date.
Whole blood can be stored at 4–8°C for up to 24 hours before the serum is separated, but it must not be frozen.
Whole blood should be allowed to clot and then centrifuged at 1000 × gravitational units (g) for 10 minutes to separate the serum. If there is no centrifuge, the blood can be kept in a refrigerator (4–8°C) until there is complete retraction of the clot from the serum (no longer than 24 hours).
The serum should be carefully removed with a fine-bore pipette to avoid extracting red cells, and transferred aseptically to a sterile vial labelled with the patient’s name or identifier, date of collection and specimen type.
A measles/rubella laboratory request form should be fully completed when the specimen is collected and must accompany all specimens sent to the laboratory.
Storage and shipment of serum samples
Serum should be stored at 4–8°C until shipment takes place, or for max. 7 days.
When kept for longer periods, serum samples should be frozen at −20°C or lower and transported to the testing laboratory on frozen ice packs. Repeated freezing and thawing of serum samples for IgM testing should be avoided, as it may have detrimental effects on the stability of IgM antibodies.
As a general rule, serum specimens should be shipped to the laboratory as soon as possible. The shipment should not be delayed for the collection of additional specimens.
Serum specimens, in their uniquely labelled, sealed vials, should be placed in sealable plastic bags or pouches containing absorbent materials such as cotton wool to soak up any leakage that may occur.