Prevalence of salivary anti-SARS-CoV-2 IgG antibodies in vaccinated children

Vaccination against COVID-19 has mitigated the impact of SARS-CoV-2 infection, decreasing the probability of progression to severe disease and death in vaccinated people. Parallel to the development and administration of COVID-19 vaccines, the immune response induced by the different vaccine platforms has been investigated, mainly, in the adult population. However, since the approval of the vaccines for use in pediatric individuals was a posteriori, vaccination began later in this population. This, added to the difficulty in obtaining blood samples from pediatric individuals, has led to less knowledge about the humoral immune response following vaccination in children. In this work, we analyzed the humoral response induced by vaccination in children through a non-invasive approach such as the measurement of specific salivary antibodies. Our results showed a high prevalence of specific salivary antibodies (81%), with the highest levels of antibodies being observed in those children who had three doses, a greater number of exposures and a shorter interval time between the last exposure to SARS-CoV-2 antigens and saliva collection. These results agree with those reported for the systemic humoral immune response in vaccinated adults, suggesting the administration of booster doses in children to maintain high antibody levels. Therefore, determination of salivary antibodies against SARS-CoV-2 could be a non-invasive tool for disease surveillance, vaccination follow-up and to assist vaccination strategies against COVID-19.