Intestinal antibody responses to two novel live attenuated type 2 oral poliovirus vaccines in healthy adults in Belgium.

In a blinded phase 1 trial (EudraCT 2017-0000908-21; NCT03430349) in Belgium, healthy adults (18 to 50 years) previously immunized exclusively with inactivated polio vaccine were administered a single dose of one of two novel type 2 oral polio vaccines (nOPV2-c1: S2/cre5/S15domV/rec1/hifi3 (N=15); nOPV2-c2: S2/S15domV/CpG40 (N=15)) and isolated for 28 days in a purpose-built containment facility. Using stool samples collected near days 0, 7, 14, and 28, we evaluated intestinal neutralization and IgA responses to the novel OPV2s and found that nOPV2-c1 and nOPV2-c2 induced detectable poliovirus type 2-specific intestinal neutralizing responses in 40.0% and 46.7% of participants respectively.