Pediatric Infectious Disease Group (GPIP) position paper on the immune debt of the COVID-19 pandemic in childhood, how can we fill the immunity gap?

Abstract

Since the beginning of the COVID-19 pandemic, reduced incidence of many viral and bacterial infections has been reported in children: bronchiolitis, varicella, measles, pertussis, pneumococcal and meningococcal invasive diseases. The purpose of this opinion paper is to discuss various situations that could lead to larger epidemics when the non-pharmaceutical interventions (NPI) imposed by the SARS-CoV-2 epidemic will no longer be necessary. While NPIs limited the transmission of SARS-CoV-2, they also reduced the spread of other pathogens during and after lockdown periods, despite the re-opening of schools since June 2020 in France. This positive collateral effect in the short term is welcome as it prevents additional overload of the healthcare system. The lack of immune stimulation due to the reduced circulation of microbial agents and to the related reduced vaccine uptake induced an "immunity debt" which could have negative consequences when the pandemic is under control and NPIs are lifted. The longer these periods of "viral or bacterial low-exposure" are, the greater the likelihood of future epidemics. This is due to a growing proportion of "susceptible" people and a declined herd immunity in the population. The observed delay in vaccination program without effective catch-up and the decrease in viral and bacterial exposures lead to a rebound risk of vaccine-preventable diseases. With a vaccination schedule that does not include vaccines against rotavirus, varicella, and serogroup B and ACYW Neisseria meningitidis , France could become more vulnerable to some of these rebound effects.

A large-scale outbreak of hand, foot and mouth disease, France, as at 28 September 2021

“…The year 2020 was, in fact, marked by a very low circulation of EV, both among hospitalised patients [8] and among children seen in primary care. In response to the COVID-19 pandemic, hygiene reinforcement may have reduced infectious contacts and immune stimulation, consequently leading to a greater susceptibility to infections in children [9]. A similar phenomenon was illustrated by the recently reported outbreak of respiratory syncytial virus (RSV) infections in Japan in July 2021 [10], which was substantially larger and earlier compared with previous years.…”

COVID-19 Pandemic Impact on Respiratory Infectious Diseases in Primary Care Practice in Children

“…A lack of immune stimulation due to personal protective measures might induce an “immunity debt” due to reduced circulation of microbial agents, which might grow in susceptible children populations and could negatively affect when the pandemic is under control ( 34 ).…”

“…The unexpected findings regarding increased NP colonization by antibiotic-resistant bacteria and changes in identified serotypes of Spn open new doors of investigation. Perhaps as the pandemic subsides, many of the handwashing and sanitizing practices will remain in place and lead to less frequent illness among children in the future, or the pandemic may produce temporary negative consequences and lead to more frequent respiratory infections because the pool of susceptible children will be larger having been unexposed for over a year ( 34 ).…”

Respiratory syncytial virus: paying the immunity debt with interest

“…Nevertheless, concerns have been raised about the potential for more severe RSV epidemics in the future due to a so-called immunity debt, a term proposed to describe the paucity of protective immunity arising from extended periods of low exposure to a given pathogen, leaving a greater proportion of the population susceptible to the disease. 2 This immunity debt is a particular concern for RSV, for which temporary immunity is obtained through exposure to the virus and maternal antibodies wane quickly; without seasonal exposure, immunity decreases and susceptibility to future, and potentially more severe, infection increases.…”