Serum antibodies of healthy people aged 18-59 years after inoculation with recombinant novel coronavirus protein vaccine(CHO cells)
Objective To evaluate the immunogenicity and immune persistence of recombinant novel coronavirus protein vaccine(CHO cells),ZF2001,at different doses and immunization procedures in healthy people aged 18-59 years.Methods We conducted a randomized,blind,placebo-controlled and phase Ⅱ clinical trial.A total of 900 healthy participants aged 18-59 years were randomly assigned to two-doses of low-dose group,two-doses of high-dose group,two-doses of placebo group,three-doses of low-dose group,three-doses of high-dose group,and three-doses of placebo group at a ratio of 1∶1∶1∶1∶1∶1 and received ZF2001 or placebo.All the participants'blood samples were collected for SARS-CoV-2 neutralizing and receptor binding domain(RBD)protein-binding antibodies detection before vaccination,14 days,six months,and 12 months after full vaccination.Results The geometric mean titers(GMTs)of neutralizing antibodies of two-doses of low-dose group,two-doses of high-dose group,two-doses of placebo group at 14 days after full vaccination were 17.7,14.1 and 2.0 respectively,and those at 6 months after full vaccination were 3.6,3.7 and 2.0 respectively.The GMTs of RBD protein-binding antibodies of the above-mentioned three groups at 14 days after full vaccination were 439.82,338.04 and 5.98 respectively,and those at 6 months after full vaccination were 63.62,50.42,and 5.67 respectively.The GMTs of neutralizing antibodies of three-doses of low-dose group,three-doses of high-dose group,and three-doses of placebo group at 14 days after full vaccination were 97.3,68.4 and 2.0 respectively,those at 6 months after full vaccination were 19.3,16.7 and 2.0 respectively,and those at 12 months after full vaccination were 7.4,7.3 and 2.0 respectively.The GMTs of RBD protein-binding antibodies of the above-mentioned three groups at 14 days after full vaccination were 1,745.67,1,107.36 and 5.84 respectively,and those at 6 months after full vaccination were 281.31,212.41 and 5.80 respectively.Conclusion ZF2001 can induce high levels of neutralizing and RBD protein-binding antibodies in the healthy participants.The immune persistence of three doses is better than that of two doses,and the immunogenicity and immune persistence of low doses are superior to those of high doses.The neutralizing antibodies at 6 months after full vaccination show a decreasing trend.A low-dose and three-dose vaccination program is recommended,and booster vaccination at 6 months after full vaccination should be considered.
severe acute respiratory syndrome coronavirus 2vaccineneutralizing antibodyimmunogenicityimmune persistence
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