MADRID – Influenza vaccination is similarly effective for individuals taking a tumor necrosis factor (TNF) inhibitor and healthy controls, but the number needed to vaccinate to prevent one case of influenza for patients taking a TNF inhibitor is much lower, according to data from a study presented at the European Congress of Rheumatology.
The number needed to vaccinate (NNV) to prevent one case of influenza among healthy control patients was 71, compared with an NNV of 10 for patients taking the TNF inhibitor adalimumab (Humira), reported, and colleagues at the University of Verona (Italy).
While TNF inhibitors “are known to increase the risk of infection by suppressing the activity of the immune system,” it has not been clear whether the response to vaccination is impaired in patients treated with a TNF inhibitor, Dr. Adami said.
Dr. Adami and colleagues reviewed data from 15,132 adult patients exposed to adalimumab in global rheumatoid arthritis clinical trials and 71,221 healthy controls from clinical trials of influenza vaccines. Overall, the rate of influenza infection was similarly reduced with vaccination in both groups. The rate in healthy individuals went from 2.3% for those unvaccinated to 0.9% for those vaccinated; for TNF inhibitor–treated patients, the rate was 14.4% for those unvaccinated versus 4.5% for those vaccinated.
“It is not surprising that the number needed to vaccinate is dramatically lower in patients treated with immunosuppressors, compared to healthy individuals,” Dr. Adami noted. “As a matter of fact, patients treated with such drugs are at higher risk of infections, namely they have a greater absolute risk of influenza. Nevertheless, [it] is quite surprising that the relative risk reduction is similar between TNF inhibitor–treated patients and healthy controls, meaning that the vaccination is efficacious in both the cohorts.”
The researchers also calculated the cost to prevent one case of influenza, using a cost of approximately 16.5 euro per vaccine. (Dr. Adami also cited an average U.S. cost of about $40/vaccine). Using this method, they estimated a cost for vaccination of 1,174 euro (roughly $1,340) to prevent one influenza infection in the general population, and a cost of about 165 euro (roughly $188) to vaccinate enough people treated with a TNF inhibitor to prevent one infection.
Dr. Adami advised clinicians to remember the low NNV for TNF inhibitor–treated patients with regard to influenza vaccination. “A direct disclosure of the NNV for these patients might help adherence to vaccinations,” he said.
Next steps for research should include extending the real-world effectiveness analysis to other medications and other diseases, such as zoster vaccination in patients treated with Janus kinase inhibitors, Dr. Adami said.
Dr. Adami had no financial conflicts to disclose. Several coauthors disclosed relationships with companies including Abiogen Pharma, Grünenthal, Amgen, Janssen-Cilag, Mundipharma, and Pfizer.
Mitchel L. Zoler contributed to this report.
SOURCE: Adami G et al. Ann Rheum Dis. Jun 2019;78(Suppl 2):192-3.