Co-administration of DTaP with COVID-19 mRNA vaccine in mice alters immune responses
During the COVID-19 pandemic, children received COVID-19 mRNA vaccines alongside other regularly scheduled immunizations such as the acellular B. pertussis vaccine DTaP. It is known that mRNA vaccines are pro-inflammatory in nature leading to protective immunity against SARS-CoV-2 infection. The goal of this study was to investigate the potential adjuvanticity of co-administration of a COVID-19 mRNA vaccine alongside DTaP. Mice were immunized with DTaP alone or with a co-administration of DTaP plus COVID-19 mRNA vaccine. To understand the impact of co-administration, we evaluated protection against B. pertussis aerosol challenge in mice and potential correlates of protection including cytokine responses to vaccination, antibody responses, and single-cell transcriptomics (scRNA) analysis of the draining lymph node. Three decreasing doses of each vaccine were used to simulate waning immunity. Overall, compared to mice immunized with DTaP, co-administration of DTaP+COVID-19 mRNA vaccines elicited higher pro-inflammatory cytokine responses, higher IgG2b antibody responses, and mice were afforded increased protection against aerosol challenge of B. pertussis. Single cell transcriptomics studies on the lymph node of vaccinated mice at one day post-boost further characterize how co-administration of COVID-19 mRNA vaccine alongside DTaP vaccine shapes immunity. Single-cell transcriptomics revealed that co-administration of DTaP and COVID-19 mRNA vaccine generated populations of B and T cells with upregulated expression of interferon-stimulated genes which were absent when vaccinating with DTaP alone. Altogether these data suggest that administering DTaP alongside COVID-19 mRNA vaccine alters immune responses and provides increased protection from an aerosol challenge of B. pertussis compared to DTaP alone in mice.