IPV-Vero vaccine induces a strong booster reaction and is well tolerated in adults

A phase 1-2 trial was conducted in 48 adults to study safety and immunogeni city of an inactivated poliovirus vaccine produced using Vero cells (IPV-Ve ro). Participants received 2 intramuscular injections with IPV-Vero (40-8-3 2 D-Ag units) 4 weeks apart. IPV-Vero was well tolerated, and induced stron g antibody; responses in all participants. At least an 8-fold titre rise ag ainst all 3 tl pes of poliovirus was found within 1 neck of the first vacci nation, indicating a strong secondary response in primed individuals. Two d ays after the first vaccination, there mas no indication for such a booster reaction. The second vaccination 4 weeks after the first dose did not furt her increase antibody levels, indicating that an immune plateau had been ac hieved after the first vaccination, The second vaccination was not reactoge nic despite the presence of these high pre-vaccination antibody levels, We conclude that IPV-Vero is well tolerated and strongly immunogenic in adults . In pre-immune adults 1 dose is enough to induce an impressive booster rea ction.