Even a seemingly minor threat like the common cold can lead to a serious illness in someone with a compromised immune system.

The Covid-19 pandemic made many people familiar with the term “immunocompromised.” But there is a broad spectrum of vulnerability, according to recent reporting in The New York Times.

Researchers have identified more than 430 so-called primary immunodeficiencies, rare conditions that are caused by genetic variants and weaken the immune system. Some of them can be detected through routine newborn screenings or other blood tests shortly after birth.

Certain chronic conditions such as multiple sclerosis, lupus, rheumatoid arthritis and AIDS can also leave people mildly immunocompromised. These diseases are often driven by an overactive immune system that starts damaging the body’s own cells, making it less capable of fighting off actual pathogens, said Carl Fichtenbaum, MD, infectious diseases professor in the Department of Internal Medicine at the University of Cincinnati College of Medicine.

He said some of these diseases are treated with high doses of steroids, which reduce inflammation but can weaken the immune system if taken for too long. Others are treated with biologic medicines, which target specific disease pathways that may indirectly affect the immune system.

Normal aging can also weaken the immune system in some ways. As people get older, they tend to produce fewer antibodies to fight off pathogens, and the defenses they do have may be deployed more slowly, said Dr. Fichtenbaum.

Click here to read the entire article in The New York Times.