Throughout the COVID-19 outbreak, numerous news reports have identified one group of people as being especially vulnerable to the virus: the immunocompromised. But what exactly does it mean to be immunocompromised?
Simply defined, it’s when your immune system isn’t performing as well as it should to keep you safe from infection—or when your immune system can’t tell the difference between normal and foreign cells.
When evaluated through a COVID-19 lens, around 3% of the population in the United States is deemed moderately-to-severely immunocompromised, putting them at a higher risk of serious illness if infected with COVID-19, even after vaccination. This is due to their immune systems’ inability to build a significant immunological response to the immunizations.
According to a March study, only roughly 56% of immunocompromised persons developed adequate levels of protection against COVID-19 after a second mRNA (Pfizer or Moderna) injection.
As a result, the Centers for Disease Control and Prevention (CDC) recommends that individuals with weakened immune systems take a second—or third—dose of the mRNA vaccines.
What does ‘immunocompromised’ mean?
To begin, it’s necessary to know what the immune system does for us.
“The immune system has two basic functions: to identify foreign tissue and to provide defense against infection,” explains Dr. Stuart Seropian, MD, a blood cancer specialist from Smilow Cancer Hospital.
“We think of a person as immunocompromised primarily when they are more vulnerable to infection than healthy individuals, because of issues with at least one of those two functions.”
What makes a person to be immunocompromised?
According to Dr. David Hafler of Yale School of Medicine, there are many ways for an individual to become immunocompromised.
He categorizes the factors into two broad categories: those who have a genetic mutation or an illness, such as HIV, that impairs immune function; and those who take certain drugs, including immunotherapy, to treat certain diseases.
Immunotherapy is a method of suppressing or dampening immune responses when the immune system is “overactive,” as in autoimmune diseases, in which immune cells target healthy tissue, or following organ transplantation. Rheumatoid arthritis, type 1 diabetes, multiple sclerosis (MS), and inflammatory bowel disease (Crohn’s and ulcerative colitis) are all autoimmune illnesses that trigger this hyperactive reaction.
“In general, the more immunocompromised someone is, the less effective vaccines will be for them,” adds Dr. Seropian.
Immunotherapy is also used to boost immune responses, often through the use of medications called “checkpoint inhibitors” to treat some types of cancer, for example. Patients treated with checkpoint inhibitors are not considered immunocompromised, Dr. Hafler notes.
“After treatment, those patients may have a perfectly normal—or even a more robust—immune response,” he says.
Because each autoimmune disease is unique, there are numerous therapeutic options, each of which has a unique effect on the immune system.
“Some therapies, such as type I interferons for MS, may actually enhance the viral immune response,” says Dr. Hafler.
“Other treatments, though, such as B cell depletion, lead to poor responses to viruses or vaccines, resulting in increases in disease and death.”
Often, it is the associated drugs that impact the immune system, not the immunotherapy itself.
“There is a cancer treatment called CAR T-Cell therapy, for example, that does not suppress the immune system; however, patients receive immunosuppressive chemotherapy before they can begin CAR T-Cell therapy,” says Dr. Seropian.
“Other forms of treatment may require that someone take a steroid medication such as prednisone to deal with side effects, and prednisone is an immunosuppressant.”
Why transplant patients are so vulnerable?
“The immune system scans the ‘barcode’ of everything in our body. And when it doesn’t recognize a new organ, for example, the T cells and B cells in our immune system will create an inflammatory reaction in an attempt to get rid of it,” according to Dr David Mulligan.
“And that’s what we call ‘rejection.’”
Organ rejection was a serious issue throughout the early years of transplant surgery. However, with the advent of current immunosuppressive drugs, Dr. Mulligan notes, it is now uncommon.
Are cancer patients immunocompromised?
Not all cancer patients are at risk.
Patients with blood cancers, such as leukemia and multiple myeloma, are more likely to receive treatment that impacts their immune system than someone with a solid tumor, says Dr. Seropian.
“There are many targeted therapies now for tumors that aren’t immunosuppressive, but with blood cancers, treatments are directed at your blood cells, which travel through your entire body. As a result, your immune system is more likely to be injured,” he says.
He adds that standard chemotherapy and radiation are believed to be less immunosuppressive than certain types of immunotherapy. Additionally, Dr. Seropian observes that the immunosuppressive effects of both medications are typically transient.
However, Dr. Seropian recommends that patients consult with their provider if they have concerns about their own risks or an immunocompromised state.
Why covid vaccines don’t work well on immunocompromised people?
Vaccination’s objective is to elicit a strong immune response against a harmless variant of a virus. Then, when the actual infection arrives, the body is prepared to defend itself. However, if a person’s immune system is impaired, that reaction may be weakened—or even disappear entirely.
“In general, the more immunocompromised someone is, the less effective vaccines will be for them,” says Dr. Seropian.
Previous research on vaccinations against other viruses, including influenza, indicates that immunocompromised individuals do not mount the same response to vaccines as healthy individuals. The same has been proven to be true with COVID-19 vaccines.
What should you do if you’re immunocompromised?
Immunocompromised people’ hygiene approaches to be safe are similar to what many of us embraced when the pandemic began. However, the level of vigilance required varies according to an individual’s immunocompromised state.
In general, Dr. Seropian says it is vital that anyone who is Dr. Seropian notes that it is critical for anyone who is immunocompromised to maintain current vaccination status—not just a third dose of the COVID-19 mRNA vaccine, but also other vaccines such as the flu and pneumococcal vaccines (which protect against pneumonia-causing bacteria). Additionally, because immunocompromised individuals have a more difficult time removing viruses from their systems, the quarantine restrictions for those classified as seriously immunocompromised are strict, he says.
What’s the bottom line? Immunocompromised patients should speak with their physicians about their unique dangers and protective measures, Dr. Seropian notes.
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