Effect of different temperature storage conditions on EBV antibody titer. Data are expressed as the percent recovery relative to the titer measured for the DBS card stored at −80°C after collection and 4 hours drying at room temperature (RT). DBS cards were kept at −20°C (open squares), room temperature (RT, ~ 22°C, black triangles), or 37°C (gray circles) for 2, 7, 14, and 21 days.