Nonspecific Effects of Infant Vaccines Make Children More Resistant to SARS-CoV-2 Infection

Abstract

A myriad of reasons, or a combination of them, have been alluded to in order to explain the lower susceptibility of children to SARS-CoV-2 infection and the development of severe forms of COVID-19. This document explores an additional factor, still little addressed in the medical literature related to the matter: nonspecific resistance to SARS-CoV-2 that could be generated by vaccines administered during childhood. The analysis carried out allows one to conclude that a group of vaccines administered during childhood is associated with a lower incidence and severity of SARS-CoV-2 infection among pediatric ages. Looking from an epidemiological perspective, this conclusion must be taken into consideration in order to ensure greater rationality in the design and implementation of prevention and control actions, including the administration of the COVID-19 vaccine, for these ages.

Clinical features of COVID-19 in Italian outpatient children and adolescents during Parental, Delta, and Omicron waves: a prospective, observational, cohort study

“…Firstly, the single-centre type of this study led to the small number of cases, limiting the analysis in the different age groups because of the relatively small sample size; however, to date, a limited number of studies described the clinical features of COVID-19 in children including the first year of the Omicron wave. Moreover, although our data did not show any differences in COVID-19 clinical manifestations between subjects who were up-to-date with routine vaccinations and children who were not, since previous studies documented a cross-reactive T-cell immune response elicited by some vaccines, such as measles-mumps-rubella (MMR) or tetanus-diphtheria-pertussis (Tdap), that mitigate COVID-19 ( 28 , 29 ). Therefore, our findings should be confirmed by larger cohorts.…”

Children’s SARS-CoV-2 Infection and Their Vaccination

“…The second factor is cross reactivity, since children tend to have a higher frequency of recurrent and concurrent viral exposure as well as vaccinations. These repeated and multiple viral infections and various early-stage vaccinations lead to an ongoing state of activation of the innate immune system [ 55 , 56 ]. Similarly, children have a higher exposure to helminth infections than adults, which causes modulation of host inflammatory components [ 57 ].…”