Impact of vaccination on the induction of mucosal immunity with mRNA vaccines against the Covid-19 epidemic

Last updated on 07 October 2024

In brief

Teams from the department of immunology at the Pitié-Salpêtrière AP-HP hospital, Inserm and Sorbonne University, coordinated by Prof Guy Gorochov, have conducted a study into the ability of Covid-19 mRNA vaccines to induce a mucosal immune response. The results of this study were published  JAMA Network Open on 23 April 2024.

The capability of intramuscular mRNA vaccines against SARS-CoV-2 to induce an antibody response in mucous membranes is still debated.

This study, based on the COVICOMPARE-M and COVICOMPARE-P trials, compares the humoral response of individuals vaccinated against Covid-19 with mRNA vaccines. Specifically, the aim is to analyse, at salivary level, the antibody response to vaccination of naïve subjects (not infected by SARS-CoV-2 before or between vaccine shots), compared with that of subjects who were infected before vaccination (pre-infected).

A total of 427 participants were included in the study, 120 of whom were pre-infected. Between February and July 2021, naïve participants received two doses of Moderna or Pfizer-BioNTech vaccine. Pre-infected participants received only one dose of Pfizer vaccine. Samples were collected before the first dose (D1), before the second (D29), then at D57 and at D180.

Salivary SARS-CoV-2 specific IgA antibodies1 were detected to a greater extent in pre-infected subjects than in naïve subjects. However, after vaccination, a small increase in IgA levels was observed in non-pre-infected participants who received the Moderna vaccine. In comparison, IgG antibodies specific to SARS-CoV-2 were widely detected in saliva after vaccination in both naïve and pre-infected subjects. In both cases, IgA and IgG antibody levels measured in saliva were highly correlated with serum levels, indicating a likely diffusion from blood to saliva.

The results of this study show that mRNA vaccination is associated with very low mucosal immunity, but at much lower levels in naïve participants. Further studies are needed to determine the association between specific salivary IgA levels and prevention of SARS-CoV-2 infection or transmission.

The COVICOMPARE-P and COVICOMPARE-M trials have been approved as a National Research Priority by the ad-hoc national steering committee for therapeutic trials and other research into the COVID-19 epidemic (CAPNET). This study was carried out with the scientific and financial support of the ANRS Emerging Infectious Diseases, the Ministry of Health and Prevention and the Ministry of Higher Education, Research and Innovation.

  1. IgA antibodies are mainly found in secretions (saliva, tears, digestive and pulmonary secretions). They are also found in the blood in much smaller quantities than IgG antibodies. Secretory IgA, the predominant form of IgA of the mucosal immune system, is found only in secretions, where it plays a particularly effective antiviral role.

Reference

Guy Gorochov, MD, PhD; Jacques Ropers, PharmD; Odile Launay, MD, PhD; Karim Dorgham, PhD; Omaira da Mata-Jardin, PhD; Said Lebbah, MD; Christine Durier, PhD; Rebecca Bauer, PhD; Anne Radenne, MSc; Corinne Desaint, PhD; Louis-Victorien Vieillard, MSc; Claire Rekacewicz, MSc; Marie Lachatre, MD; Béatrice Parfait, MD, PhD; Frédéric Batteux, MD, PhD; Philippe Hupé, PhD; Läétitia Ninove, MD; Maeva Lefebvre, MD; Anne Conrad, MD, PhD; Bertrand Dussol, MD, PhD; Zoha Maakaroun-Vermesse, MD; Giovanna Melica, MD; Jean-François Nicolas, MD, PhD; Renaud Verdon, MD, PhD; Jean-Jacques Kiladjian, MD, PhD; Paul Loubet, MD, PhD; Catherine Schmidt-Mutter, MD, PhD; Christian Dualé, MD, PhD; Séverine Ansart, MD, PhD; Elisabeth Botelho-Nevers, MD, PhD; Jean-Daniel Lelièvre, MD, PhD; Xavier de Lamballerie, MD, PhD; Marie-Paule Kieny, PhD; Eric Tartour, MD, PhD; Stéphane Paul, PhD – JAMA Network Open