An inactivated poliovirus vaccine using Sabin strains produced on the serum-free PER.C6® cell culture platform is immunogenic and safe in a non-human primate model

30-Year Development of Inactivated Virus Vaccine in China

Inactivated vaccines are vaccines made from inactivated pathogens, typically achieved by using chemical or physical methods to destroy the virus's ability to replicate. This type of vaccine can induce the immune system to produce an immune response against specific pathogens, thus protecting the body from infection. In China, the manufacturing of inactivated vaccines has a long history and holds significant importance among all the vaccines available in the country. This type of vaccine is widely used in the prevention and control of infectious diseases. China is dedicated to conducting research on new inactivated vaccines, actively promoting the large-scale production of inactivated vaccines, and continuously improving production technology and quality management. These efforts enable China to meet the domestic demand for inactivated vaccines and gain a certain competitive advantage in the international market. In the future, China will continue to devote itself to the research and production of inactivated vaccines, further enhancing the population's health levels and contributing to social development. This study presents a comprehensive overview of the 30-year evolution of inactivated virus vaccines in China, serving as a reference for the development and production of such vaccines.

Safety and immunogenicity of 3 formulations of a Sabin inactivated poliovirus vaccine produced on the PER.C6® cell line: A phase 2, double-blind, randomized, controlled study in infants vaccinated at 6, 10 and 14 weeks of age

An inactivated poliovirus vaccine candidate using Sabin strains (sIPV) grown on the PER.C6® cell line was assessed in infants after demonstrated immunogenicity and safety in adults. The study recruited 300 infants who were randomized (1:1:1:1) to receive one of 3 dose levels of sIPV or a conventional IPV based on Salk strains (cIPV). Poliovirus-neutralizing antibodies were measured before the first dose and 28 days after the third dose. Reactogenicity was assessed for 7 days and unsolicited adverse events (AEs) for 28 days after each vaccination. Serious AEs (SAEs) were recorded throughout the study. Solicited AEs were mostly mild to moderate. None of the SAEs reported in the study were judged vaccine related, including one fatal SAE due to aspiration of vomitus that occurred 26 days after the third dose of low-dose sIPV. After 3 sIPV vaccinations and across all dose levels, seroconversion (SC) rates were at least 92% against Sabin poliovirus types and at least 80% against Salk types, with a dose-response in neutralizing antibody geometric mean titers (GMTs) observed across the 3 sIPV groups. Compared to cIPV, the 3 sIPV groups displayed similar or higher SC rates and GMTs against the 3 Sabin types but showed a lower response against Salk types 1 and 2; this was most visible for Salk type 1. While the PER.C6® cell line-based sIPV showed an acceptable safety profile and immunogenicity in infants, lower seroprotection against type 1 warrants optimization of dose level and additional clinical evaluation.

Safety and immunogenicity of a new Sabin inactivated poliovirus vaccine candidate produced on the PER.C6® cell-line: a phase 1 randomized controlled trial in adults

This first-in-human study (NCT03032588), conducted in Belgium, evaluated a new inactivated poliovirus vaccines (IPV) candidate based on Sabin poliovirus strains grown on the high-yield PER.C6® cell line. Healthy adults (N = 32) were randomized (1:1) to receive a single dose of PER.C6-based Sabin-IPV (sIPV, 15:35:112.5 DU/dose) or conventional Salk-IPV (cIPV, 40:8:32 DU/dose). Reactogenicity was assessed up to 7 days after vaccination, immunogenicity 28 days after vaccination, and safety up to 6 months after vaccination.Solicited adverse events (AEs) were mild to moderate, no changes of concern in vital signs or safety laboratory values were observed, and no severe AEs (SAEs) or vaccine-related unsolicited AEs were reported after vaccination. A trend to more frequent solicited AEs after sIPV than after cIPV administration was observed. Most participants had preexisting neutralizing antibodies against poliovirus types (titer ≥8), which were strongly boosted by sIPV. Post-vaccination geometric mean titers were high (≥12,000) and similar across the two vaccination groups. Only participants with very high preexisting antibody levels did not show a vaccine-induced response, defined in seropositive participants as a 4-fold titer increase. The 10 initially seronegative (titer <8) participants (n = 5 in each study group) seroconverted and all participants had seroprotective antibody levels post-vaccination. The antibodies elicited by sIPV neutralized both Sabin and Salk poliovirus strains.In conclusion, the PER.C6®-based sIPV was well tolerated and highly immunogenic in adults with preexisting antibodies to poliovirus.

Vaccination Schedules and COVID-19 Risk

A significant difference in the number of novel coronavirus 2019 (COVID-19) cases and mortality has been noted among different World Health Organization (WHO) regions and countries. We compared the vaccination schedules for 2 countries from WHO Europe Region (Italy and Spain) and 2 countries from WHO Regional Office for the Eastern Mediterranean (Iran and Egypt). Both Iran and Egypt included the Sabin vaccine as part of the obligatory vaccination programs; meanwhile, Italy and Spain used the Salk vaccine. Recently, Iran and Egypt added a single dose of the Salk vaccine to the 6-7 doses of Sabin vaccine because of the new evidence showing that the use of the Salk vaccine in conjunction with Sabin vaccine achieves better mucosal immunity. Italy and Spain used an acellular vaccine against pertussis. Meanwhile, Iran and Egypt used a whole-cell vaccine. Taking into consideration the lower number of deaths in Iran and Egypt compared to Italy and Spain, we could hypothesize that the whole-cell pertussis vaccine could have a cross-immunity against COVID-19. Further research is warranted to identify the main reasons for the lower number of COVID-19 cases and deaths in certain countries in order to control COVID-19.

In-Vitro Inactivation of Sabin-Polioviruses for Development of Safe and Effective Polio Vaccine

After years of global collaboration; we are steps away from a polio-free world. However, the currently conventional inactivated polio vaccine (cIPV) is suboptimal for the post eradication era. cIPV production cost and biosafety hazards hinder its availability and coverage of the global demands. Production of IPV from the attenuated Sabin strains (sIPV) was an ideal solution and scientists work extensively to perfect a safe, effective and affordable sIPV. This study investigated the ability of hydrogen peroxide (H₂O₂), ascorbic acid (AA) and epigallocatechin-3-gallate (EGCG) as alternatives for Formaldehyde (HCHO) to inactivate Sabin-polioviruses strains for sIPV production. Sabin-polioviruses vaccine strains were individually treated with AA, EGCG or H₂O₂ and were compared to HCHO. This was investigated by determination of the inactivation kinetics on HEP_2C cells, testing of D-antigen preservation by ELISA and the immune response in Wistar rats of the four vaccine preparations. H₂O₂, AA and EGCG were able to inactivate polioviruses within 24 h while HCHO required 96 h. Significant high D-antigen levels were observed using AA, EGCG and H₂O₂ compared to HCHO. Rat sera tested for neutralizing antibodies showed comparable results. These findings support the idea of using these inactivating agents as safe and time- saving alternatives for HCHO to produce sIPV.

Skin delivery of trivalent Sabin inactivated poliovirus vaccine using dissolvable microneedle patches induces neutralizing antibodies

The cessation of the oral poliovirus vaccine (OPV) and the inclusion of inactivated poliovirus (IPV) into all routine immunization programmes, strengthens the need for new IPV options. Several novel delivery technologies are being assessed that permit simple yet efficacious and potentially dose-sparing administration of IPV. Current disadvantages of conventional liquid IPV include the dependence on cold chain and the need for injection, resulting in high costs, production of hazardous sharps waste and requiring sufficiently trained personnel. In the current study, a dissolvable microneedle (DMN) patch for skin administration that incorporates trivalent inactivated Sabin poliovirus vaccine (sIPV) was developed. Microneedles were physically stable in the ambient environment for at least 30 min and efficiently penetrated skin. Polio-specific IgG antibodies that were able to neutralize the virus were induced in rats upon administration using trivalent sIPV-containing microneedle patches. These sIPV-patch-induced neutralizing antibody responses were comparable to higher vaccine doses delivered intramuscularly for type 1 and type 3 poliovirus serotypes. Moreover, applying the patches to the flank elicited a significantly higher antibody response compared to their administration to the ear. This study progresses the development of a skin patch-based technology that would simplify vaccine administration of Sabin IPV and thereby overcome logistic issues currently constraining poliovirus eradication campaigns.