Quarantine May Negatively Affect Kids’ Immune Systems

By Donna L. Farber and Thomas Connors. Dr. Farber is a professor of immunology and surgery at Columbia University Vagelos College of Physicians and Surgeons, where Dr. Connors is an assistant professor of pediatrics. Excerpts:

"During the Covid-19 pandemic, the world is unwittingly conducting what amounts to the largest immunological experiment in history on our own children. We have been keeping children inside, relentlessly sanitizing their living spaces and their hands and largely isolating them. In doing so, we have prevented large numbers of them from becoming infected or transmitting the virus. But in the course of social distancing to mitigate the spread, we may also be unintentionally inhibiting the proper development of children’s immune systems."

"While the immune system is influenced by multiple factors, including genetics and everyday exposures to family members and pets, the long term effects of removing the social system that brings children in contact with other people, places and things remains uncharted territory. However, there is now substantial evidence that antigen exposure during the formative period of childhood is important not only for protection but also for reducing the incidence of allergies, asthma and inflammatory diseases. A well-known theory, called the “hygiene hypothesis,” proposes that the increased incidence of allergies and other immune disorders involving inappropriate immune reactions across industrialized societies is a result of the move away from agrarian society toward a highly sanitized urban setting.

Failing to train our immune systems properly can have serious consequences. When laboratory mice raised in nearly sterile conditions were housed together in the same cage with pet mice raised in standard conditions, some of the laboratory mice succumbed to pathogens that the pet mice were able to fight off. Additional studies of the microbiome — the bacteria that normally inhabit our intestines and other sites — have shown that mice raised in germ-free conditions or in the presence of antibiotics had reduced and altered immune responses to many types of pathogens. These studies suggest that for establishing a healthy immune system, the more diverse and frequent the encounters with antigens, the better.

Clinical trials have already demonstrated the effect of antigen exposure or avoidance in early childhood on subsequent immune responses. Introduction of peanuts to infants resulted in reduced incidence of peanut allergy, while avoidance had the opposite effect of promoting unwanted, severe allergic immune responses to peanuts. These findings further suggest that exposure during the formative years is critical for developing an immune system that responds appropriately to pathogens while tolerating harmless antigens."