People taking immunosuppressive drugs benefit significantly from SARS-CoV-2 vaccines approved in the United States to prevent and reduce the severity of COVID-19, according to the first study to quantify the vaccines’ real-world effectiveness in this population.
Researchers’ analysis of the electronic medical records of more than 150,000 people in the University of Michigan’s health care system showed that even after becoming fully vaccinated, immunosuppressed individuals remain at higher risk for COVID-19 than are vaccinated people in the wider population who aren’t receiving immunosuppressive therapy. However, they still derive benefit from vaccination, particularly when bolstered with a booster dose.
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The study, published online in Annals of the Rheumatic Diseases, also claims to be the first to show that the Moderna (mRNA-1273) vaccine is as effective as the Pfizer-BioNTech (BNT162b2) vaccine for people taking immunosuppressants.
“Booster doses are effective and important for individuals on immunosuppressants,” corresponding author Lili Zhao, PhD, a research associate professor in biostatistics at the University of Michigan, Ann Arbor, said in an interview. “Previous studies focused mostly on the Pfizer vaccine, whereas our study is the first that also investigates the Moderna vaccine in a large, immunosuppressed population.”
The epidemiologic study included 154,519 fully vaccinated and unvaccinated adults in the Michigan Medicine electronic health record database. Participants were considered fully vaccinated if they were within 2 weeks of having received a second dose of the Pfizer-BioNTech and Moderna vaccines or the single-dose Johnson & Johnson (Ad26.COV2.S) vaccine. The study population included 5,536 immunosuppressed patients; of those, 4,283 were fully vaccinated, and 1,253 were unvaccinated.
The researchers focused on data collected from Jan. 1 to Dec. 7, 2021, so the study doesn’t cover the Omicron variant. “The conclusions for immunosuppressed individuals are likely to remain the same during the Omicron period,” Dr. Zhao said. “We are currently investigating this.” Johnson & Johnson paused production of its vaccine in February.
Dr. Lili Zhao
The researchers found that, among unvaccinated individuals, the immunosuppressed group had about a 40% higher risk of infection than did the immunocompetent patients (hazard ratio, 1.398; 95% confidence interval, 1.068-1.829; P = .0075) but a similar risk of COVID-19 hospitalization (HR, 0.951; 95% CI, 0.435-2.080; P = .9984). For the fully vaccinated, the gap was significantly wider: Immunosuppressed patients had more than double the risk of infection (HR, 2.173; 95% CI, 1.690-2.794; P < .0001) and almost five times the risk of hospitalization (HR, 4.861; 95% CI, 2.238-10.56; P < .0001), compared with immunocompetent patients.
However, among immunosuppressed individuals, the vaccinations significantly lowered risks, compared with not being vaccinated. There was a statistically significant 45% lower risk of infection (HR, 0.550; 95% CI, 0.387-0.781; P = .001) and similarly lower risk of hospitalization that did not reach statistical significance (HR, 0.534; 95% CI, 0.196-1.452; P = .3724).
When those immunosuppressed patients received a booster dose, their protection against COVID-19 improved, compared with their immunosuppressed counterparts who didn’t get a booster, with a 58% lower risk of infection after adjustment for age, gender, race, and Charlson Comorbidity Index (adjusted HR, 0.42; 95% CI, 0.24-0.76; P = .0037). The study included nearly 4 months of data after the Centers for Disease Control and Prevention recommended a booster dose of the Moderna and Pfizer-BioNTech vaccines for immunocompromised individuals in August 2021. Among the immunosuppressed patients, 38.5% had received a booster dose.
There also was no apparent difference in the effectiveness between the Moderna and Pfizer-BioNTech vaccines, with adjusted hazard ratios showing 41%-48% lower risk of infection. Too few individuals in the study were vaccinated with the Johnson & Johnson vaccine to enable a sufficiently powered calculation of its effectiveness.