Testing of IVIG
SARS-CoV-2 nAb titers were below the limit of detection for all 54 IVIG lots tested, irrespective of geographic origin of the plasma (Europe vs United States) and plasma collection modality (recovered vs source) (Figure 1A).
Figure 1.  Coronavirus neutralizing antibody titers in IVIG lots (n = 54) against (A) SARS-CoV-2 and (B) HCoV-229E. The IVIG lots were manufactured from plasma either donated by plasmapheresis (S), or recovered from whole blood donations (R), in the United States or central Europe. Each dot represents the mean of 2 independent experiments, except in (B) from 1 EU-R IVIG lot the titer of a single determination is shown. The lines represent the median in each group. Paired t tests were used for determination of significance. Abbreviation: EU, Europe; HCoV, human coronavirus; IVIG, intravenous immunoglobulin; LOD, limit of detection; µNT50, 50% neutralization titer; R, recovered; S, source; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2. In contrast, HCoV-229E nAb titers between 1:43 and 1:196 (mean = 1:98) were measured for the 54 IVIG lots tested (Figure 1B). IVIG lots produced from recovered plasma contained significantly higher levels of nAb to HCoV-229E as compared to IVIG lots produced from source plasma, independent of the geographic origin. A significant, although quantitatively minor, difference was also found between IVIG lots manufactured from source plasma collected in either the United States or Europe.