Intra-muscular mRNA vaccines are poor inducers of mucosal immunity 28 April 2024

Intra-muscular mRNA vaccines are poor inducers of mucosal immunity

Surprisingly, there is still considerable controversy in the literature regarding the capacity of intra-muscular mRNA vaccination to induce a mucosal immune response. This national-wide cohort study (part of COVICOMPARE M and COVICOMPARE P trials) compared serum and salivary IgG and IgA levels among mRNA-vaccinated individuals who were, or not, previously infected by SARS-CoV-2.  The study concludes that specific salivary IgA can be detected after mRNA vaccination solely, but to much lower levels than in previously infected individuals. Further studies are needed to determine the relationship between secretory IgA levels and prevention against infection or transmission. A mucosal route of vaccine administration might have to be considered in order to build robust local immunity.

The CoviCompare M and CoviCompare P trials has been labeled as a National Research Priority by the National Orientation Committee for Therapeutic Trials and other researches on Covid-19 (CAPNET). The study has been conducted by the F-CRIN I-REIVAC network of excellence in clinical investigation and vaccinology with scientific and financial support from the Ministère des Solidarités et de la Santé and Ministère de l’Enseignement Supérieur, de la Recherche et de l’Innovation and ANRS Maladies Infectieuses Émergentes.