Comparison of capillary blood versus venous blood samples in the assessment of immunity to measles

Seroepidemiological investigations are essential for assessing the efficacy of measles vaccination programmes. However, when large-scale sampling is needed, a major difficulty is the problem of taking venous blood, especially in children. An alternative method is the collection of capillary blood samples spotted on filter papers. The eluted extract from these 'blood' spots can be used instead of serum samples for measles laboratory diagnosis or investigations. Measles antibody detection is readily carried out by ELISA on serum samples. The same technique can be used on eluates from capillary blood spots. Measles antibody titres determined on matched serum and blood spot samples from 27 children were compared. A strong correlation was found between the results obtained with the two methods of blood sampling.