How Cosentyx Works on the Immune System
Cosentyx (secukinumab) is a monoclonal antibody that targets interleukin-17A (IL-17A), a protein driving inflammation in autoimmune conditions like psoriasis, psoriatic arthritis, and ankylosing spondylitis. By blocking IL-17A, it reduces excessive immune responses that attack healthy tissues.[1]
Does It Suppress Overall Natural Immunity?
No, Cosentyx does not broadly suppress natural immunity like corticosteroids or broad immunosuppressants (e.g., methotrexate). It selectively inhibits a specific inflammatory pathway (IL-17/Th17 axis) without affecting other immune arms, such as T-cell proliferation or antibody production. Clinical trials show it preserves responses to vaccines and fights most infections normally.[1][2]
Increased Infection Risks Patients Face
While targeted, Cosentyx raises susceptibility to certain infections:
- Upper respiratory infections (most common, ~10-15% of patients).
- Candida infections (oral or esophageal, due to IL-17's role in antifungal defense; 3-5% incidence).
- Rare serious cases like tuberculosis reactivation (screening required pre-treatment).[1][3]
It does not significantly increase risks for viral infections (e.g., flu, COVID-19) or bacterial pneumonia compared to placebo.
| Infection Type | Risk Increase vs. Placebo |
|----------------|---------------------------|
| Upper respiratory | Mild (11% vs. 9%)[2] |
| Candida | Moderate (3.6% vs. 1.5%)[3] |
| Serious (TB, sepsis) | Low (0.7% vs. 0.5%)[1] |
Vaccine Response While on Cosentyx
Patients maintain immunity to non-live vaccines:
- Tetanus and pneumococcal vaccines elicit normal antibody levels.
- Avoid live vaccines (e.g., shingles, MMR) due to theoretical risk.[1][4]
Long-Term Effects on Immunity
Over 5+ years in extension studies, no evidence of cumulative immune weakening or higher malignancy rates emerges. Natural immunity rebounds fully after stopping treatment (half-life ~27 days).[2][5]
Who Should Avoid Cosentyx?
Active infections, untreated TB, or recent live vaccines. Monitor for new symptoms; benefits often outweigh risks in moderate-severe disease.[1]
[1]: Cosentyx Prescribing Information (Novartis)
[2]: NEJM: Secukinumab Phase 3 Trials (2014)
[3]: FDA Label Update (2023)
[4]: EULAR Recommendations on Vaccination (2022)
[5]: Long-term Safety Review, Lancet (2020)