In a recent study published in Immunology & Cell Biology, scientists examine the protective efficacy of coronavirus disease 2019 (COVID-19) vaccine-induced mucosal antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs).
Study: Mucosal antibody responses following Vaxzevria vaccination. Image Credit: ANDRES MENA PHOTOS / Shutterstock.com
Background
Mucosal linings in the eyes, nose, mouth, and throat act as the first line of defense against invading respiratory pathogens, such as SARS-CoV-2. Previous studies have indicated that SARS-CoV-2 spike protein-specific mucosal immunoglobulin A (IgA) antibodies can provide strong protection against breakthrough COVID-19 infections and novel viral variants.
Intramuscularly-administered adenoviral vector-based COVID-19 vaccines have been shown to induce weak mucosal immune responses in infection-naïve individuals. In this context, a recent study reported that the adenoviral vector-based COVID-19 vaccine Vaxzevria induces higher levels of mucosal IgG and IgA antibodies in COVID-19-recovered individuals compared to infection-naïve individuals.
In the current study, scientists compare plasma and mucosal antibody levels from saliva and tear samples, respectively. The ability of these antibodies to induce Fc effector functions and cross-react with SARS-CoV-2 variants among Vaxzevria-vaccinated individuals with or without prior SARS-CoV-2 infection was also determined. Furthermore, the researchers evaluated how viral exposure impacts mucosal antibody responses after Vaxzevria vaccination.
Important observations
COVID-19-recovered individuals exhibited IgG responses in both saliva and plasma samples after a single dose of the Vaxzevria vaccine as compared to infection-naïve individuals who received two vaccine doses. Moreover, COVID-19-recovered individuals exhibited significantly higher spike-specific engagements of Fc-receptors and spike-specific salivary IgA1 responses after the first