St. Louis, MO—The good news is that COVID-19 vaccination sparked antibody responses in nearly 90% of recipients with weakened immune systems. The bad news, however, is that their responses were only about one-third as strong as those mounted by healthy people, according to a new study.

The results make a strong argument for a third “booster” dose of mRNA vaccines in immunocompromised patients, according to Washington University School of Medicine–led researchers.

The study published in the Annals of Internal Medicine involved taking at least one immune-suppressing medication for illnesses such as inflammatory bowel disease, rheumatoid arthritis, spondyloarthritis, lupus, and multiple sclerosis.

Because no one knows the minimum level of antibodies required for protection, researchers weren’t able to assess whether the immune response was adequate. The The CDC recently recommended, however, that patients taking immunosuppressants receive a third dose of the vaccine to boost their immune responses.

“Some of our patients have been hesitant about getting vaccinated, which is unfortunate because they are at increased risk of having more severe cases of COVID-19 if they happen to get infected, compared to those not taking immune-suppressing drugs,” said cosenior author Alfred Kim, MD, PhD, an assistant professor of medicine who treats patients with autoimmune conditions at Barnes-Jewish Hospital. “Some of them are worried that vaccination might cause their disease to flare, but we haven’t seen that happen. Others don’t see the point of vaccination, because they think the drugs they’re taking to treat their autoimmune condition will prevent them from producing an immune response to the vaccine. What we found here is that the vast majority of immunocompromised patients with autoimmune diseases are able to mount antibody responses following COVID-19 vaccination. There’s clearly a benefit for this population.”

Dr. Kim notes that previous studies have indicated that immunosuppressive medications can lessen responses to other vaccines, such as those for influenza and pneumococcal diseases. At the same time, according to the study, although mRNA-based SARS-CoV-2 vaccinations provide some protection in immunocompetent recipients, immunogenicity in immunosuppressed patients with chronic inflammatory diseases (CID) remains unclear.

The prospective observational cohort study was conducted at two U.S. referral centers for CID patients. The volunteer sample of adults with confirmed CID eligible for early COVID-19 vaccination included hospital employees of any age, as well as patients older than age 65 years. Immunocompetent participants were recruited separately from hospital employees.

All participants received two doses of mRNA vaccine against SARS-CoV-2 between December 10, 2020, and March 20, 2021.

Participants were assessed within 2 weeks before vaccination and 20 days after the final vaccination. The study team was seeking to analyze anti–SARS-CoV-2 spike (S) IgG+ binding in all participants, and neutralizing antibody titers and circulating S-specific plasmablasts in a subset to assess humoral response after vaccination.

Results indicate that most of the 133 participants with CID (88.7%) and all 53 immunocompetent participants developed antibodies in response to mRNA-based SARS-CoV-2 vaccination. Some with CID developed numerically lower titers of anti-S IgG, however.

The study found that anti-S IgG antibody titers after vaccination were lower in 17 participants with CID receiving glucocorticoids than in those not receiving them. Researchers report that the geometric mean of anti-S IgG antibodies was 357 (95% CI, 96-1324) for participants receiving prednisone versus 2,190 (CI, 1598-3002) for those not receiving it.

They note that anti-S IgG antibody titers were also lower in 10 participants receiving B-cell depletion therapy (BCDT).

“Measures of immunogenicity differed numerically between those who were and those who were not receiving antimetabolites (n = 48), tumor necrosis factor inhibitors (n = 39), and Janus kinase inhibitors (n = 11); however, 95% CIs were wide and overlapped,” the researchers write. “Neutralization titers seemed generally consistent with anti-S IgG results. Results were not adjusted for differences in baseline clinical factors, including other immunosuppressant therapies.”

The study team advises that, compared with nonusers, patients with CID treated with glucocorticoids and BCDT seem to have lower SARS-CoV-2 vaccine–induced antibody responses. Researchers conceded their sample was small and call for confirmation in a larger study.

“Receiving this additional dose may help mitigate this loss of response,” Dr. Kim said. “It’s really important for people who are immunocompromised to receive this dose to maximize their ability to protect themselves from SARS-CoV-2.”

The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.