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Immunocompromised People Produce Fewer Antibodies When Vaccinated, May Need Boosters

A nurse gives a shot of the Pfizer vaccine to a patient in February at a mass vaccination site in Ferguson.
File photo / David Kovaluk
St. Louis Public Radio
A nurse gives a shot of the Pfizer vaccine to a patient in February at a mass vaccination site in Ferguson.

As new coronavirus infections continue to climb and fast-spreading variants sweep the U.S., millions of Americans with autoimmune diseases are at risk.

Patients with these chronic conditions, such as rheumatoid arthritis or lupus, often take medications that tamp down on their immune response — rendering some vaccinations less effective.

New research from Washington University and the University of California-San Francisco finds nearly 90% of immunosuppressed patients vaccinated for the coronavirus produced infection-fighting antibodies. But their immune response was weaker than that of healthy patients, lending support to a recent federal recommendation that immunocompromised patients get a third vaccine shot.

Immunocompromised people account for about 3% of the U.S. population, including people with multiple sclerosis and inflammatory bowel diseases.

These patients are at higher risk of becoming severely ill from COVID-19, according to the Centers for Disease Control and Prevention. Small studies in the U.S. and Israel have reported 40% to 44% of vaccinated people hospitalized for COVID-19 were immunocompromised.

That’s not necessarily surprising, said Alfred Kim, a rheumatologist at Washington University School of Medicine and co-author of the study.

“We’ve known for a long time that people who are immunosuppressed are generally at increased risk of infection,” Kim said. “We put a cap with immune suppression drugs on the vigor of their immune response.”

Kim, who treats patients with autoimmune diseases at Barnes-Jewish Hospital, worried that those taking immunosuppressive drugs may not respond to the coronavirus vaccines. Previous studies have shown vaccinations against influenza and other viruses are less effective when given to patients with weakened immune systems.

Using blood samples collected from 133 patients taking immune-suppressing medications before and after vaccination, Kim and his colleagues found the vast majority, about 89%, produced antibodies against the coronavirus.

“This is very encouraging, because it shows overall, across numerous different types of immunosuppressive medications, that most of our subjects were able to generate a response that could lead to protection,” Kim said.

Still, immunosuppressed patients in the study only produced about one-third the number of antibodies and antibody-producing cells in response to vaccination compared to healthy patients.

Patients on certain immunosuppressive drugs had particularly low antibody responses, including Rituxan, a medication used to treat rheumatoid arthritis and multiple sclerosis, and prednisone, a common anti-inflammatory drug.

The results are in line with related research, said Florian Krammer, a professor of microbiology at Mount Sinai who was not involved in the study. Though a weaker immune response is concerning, he said, it’s unclear what level of antibody response is needed to protect against the coronavirus.

“It doesn't necessarily mean that all your protection goes away, because you have a lower response,” Krammer said. “Of course, if you see that somebody on a specific drug has a response that's lower than a healthy person, you might want to give that person another dose of the vaccine to make sure they have optimal protection.”

The Washington University research team is now following the same study participants as they receive a third coronavirus vaccine dose.

Follow Shahla on Twitter: @shahlafarzan

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