Getting vaccinated gives us protection against COVID, but not everyone experiences the same sense of security, because research suggests vaccine efficacy may vary. The pharmaceutical companies producing the COVID shots excluded people who were taking immunosuppressive medication from clinical trials, so scientists are still not sure how well current vaccines work for these individuals. Experts are now relying on emerging research to see how people taking immunosuppressive drugs fare against COVID after being fully vaccinated, and the news may not be good for millions of U.S. adults. Recent research estimates that nearly six million Americans are taking immunosuppressants that could reduce their vaccine response.
A study published May 20 in JAMA Network Open analyzed data for U.S. adults aged 18 to 64 from Jan. 2017 through Dec. 2019 using Clinformatics Data Mart, a national commercial claims database of more than three million Americans, to see how many took immunosuppressants.
Beth Wallace, MD, the study's corresponding author and a rheumatologist with the University of Michigan Medical School, told CNN that through her research, she estimates six million Americans are currently taking immunosuppressants that could reduce vaccine response. Wallace noted that this is likely a conservative estimate, as her study did not include people who are on Medicare.
Unfortunately, several studies have recently shown that people on immunosuppressants may have a reduced vaccine response. A May 5 JAMA study led by a team of researchers at Johns Hopkins University School analyzed the vaccine response of more than 650 organ transplant recipients who were taking medicines to suppress their immune system, and found that 46 percent had no antibody response after two doses of Pfizer or Moderna.
Another study from the Washington University School of Medicine—preprinted April 9 on medRxiv—analyzed nearly 200 patients with various conditions such as lupus, psoriasis, and inflammatory bowel syndrome, and found that two particular immunosuppressant medicines (glucocorticoids and B cell depleting agents) "substantially" impaired vaccine-included immunity to COVID from mRNA vaccines.
"No one really anticipated the vaccine responses would look so bad," Kathryn Stephenson, MD, an infectious disease specialist and assistant professor at Harvard Medical School who was not involved in either of the three studies, told CNN.
This may not mean individuals taking immunosuppressants are not protected, however. Experts don't know exactly how vaccine response correlates to protection against COVID. Both the U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) advise patients against taking tests to check for antibodies following vaccination, because the results may not accurately determine someone's level of protection.
"For those patients who do not have antibodies or do not produce as robust an antibody response, we don't yet know if you will be protected," the Leukemia&Lymphoma Society explained to CNN in a statement. "There are other types of immunity which may provide protection. Immune cells known as T cells may play a role in the ability of our immune system to protect us against COVID-19."