Antibody-Dependent Enhancement (ADE)

• Vaccines could possibly make the infection worse or more severe
• Vaccines for MERS-CoV and SARS-CoV have had instances of ADE
• Not observed in non-human trials of rhesus macaques Vaccine-Associated Enhanced Respiratory Disease (VAERD)
• reported in young children when treated with alum adjuvant in the vaccine when tested for measles and respiratory syncytial virus.
• no evidence of inactivated virus vaccine with alum
• alum may reduce immunopathology compared to unadjuvanted vaccines Limitations
• Interim analysis was added during the study to provide design for phase 3.
• The full analysis of the entire trial population is needed to get a full grasp of the inactivated vaccine (including tolerability, immunogenicity, and immune persistence).
• Full protection from COVID-19 specifically is unknown, inactivated vaccine just provided robust antibody responses.