Vaccines and Immunization

Biography

Biography: Qiyi(chee-e)

Abstract

Background: Molecular evidence has shown poliovirus vaccination induces an adaptive humoral immune response. In vitro experiments of polio-immune sera have been examined retrospectively in the context of the COVID-19 pandemic, but the induced antibodies that may cross-react with SARS-CoV-2 have yet to be analyzed in a controlled and prospective manner.

Objective: To evaluate and characterize the immune response to SARS-CoV-2 elicited in adults by IPV (inactivated poliovirus vaccine).

Design: Single arm, open-label, pre-post vaccine immunogenicity trial

Setting: San Diego, CA (USA), November 2020 on going.

Participants: Adults between the ages of 18-80 with no active infectious disease, history of COVID-19 or prior COVID-19 vaccination.

Interventions: All participants received IPV (IPOL, Sanofi Pasteur) by intramuscular injection.

Measurements: Blood specimens collected at baseline (pre-inoculation) and 28±3 days post-inoculation were tested for polio antigens using Enzyme-Linked Immunosorbent Assays (ELISA). Viral replication via RNA-dependent RNA polymerase (RdRp) enzymatic activity was measured to the polio-immunized sera.

Results: A total of 298 of the 300 enrolled participants completed both on-site visits. Comparing the baseline (Day 1) and Day 28 measurements, 261 of the 298 paired samples (87.6%) demonstrated a positive increase in antibody titers, 30 (10.1%) decreased and 7 (2.3%) had no change. Samples that demonstrated no change or a decrease in titers from pre- to post-inoculation had high titer levels at baseline. Of the 298 polio-immune serum samples, 47 were randomly selected for RdRp enzymatic activity testing, and all samples (100%) demonstrated inhibition of RdRp function, inhibition of SARS-CoV-2-induced Cyto Pathic Effects (CPE) in Vero cell culture, and a clear demonstration that IPV immunization raises antibodies that recognize the RNA-dependent-RNA-polymerase (RdRp) proteins of both poliovirus and SARS-CoV-2. Additionally, our retrospective study demonstrated adults re-immunized with IPV exhibited similar antibody responses to both poliovirus and SARS-CoV-2 RdRp, compared to children who received IPV as part of their childhood vaccinations. Across all ages, poliovirus vaccination produces antibodies that inhibit RdRp function, thereby preventing viral replication that may cause disease progression in infected individuals. The study results provide robust data that poliovirus vaccines can generate strong adaptive immune responses against SARS-CoV-2, providing protection from infection. Serologically, we found poliovirus vaccination significantly increases antibody titers (p<0.0001). Clinically, only 1.67% of the studied population reported testing positive for COVID-19, which can be compared to the local infection rate among the general population at that time, 8.83% (p<0.0001, z=4.677 [95% CI (0.54,3.85)]). Those who did test positive for COVID-19 only experienced mild symptoms for 1-3 days, if at all. Moreover, no one in the clinical trial was hospitalized (0%) or died (0%) due to COVID-19, which may be compared to the rates in the local population, with 5.5% of the general public being hospitalized and 1.3% dying from COVID-19 (p<0.0001, z=6.21; p<0.01, z=2.73, respectively).

Limitations: Participants were not routinely tested for COVID-19, though known exposures were reported, and COVID-19 PCR results were documented.

Conclusion: A single dose of IPV induces a significant increase in antibody titers, which can cross-react with SARS-CoV-2. This prospective clinical trial confirms findings from retrospective studies that polio-immune sera demonstrate inhibition of viral replication and IPV can affect SARS-CoV-2 RdRp reactivity.