Meds & Escalation
If you have Crohn's disease and take immunosuppressive medications, vaccines require more thought than they do for most people. Some vaccines are completely safe regardless of what you're on. Others, specifically live vaccines, can pose real risks when your immune system is being deliberately suppressed. The rules vary by medication, and getting them wrong can mean either an unnecessary infection or an avoidable complication. Here's what you need to know, organized by the questions Crohn's patients actually ask.
Why Immunosuppression Changes the Vaccine Calculus
Vaccines work by training your immune system to recognize a pathogen. Inactivated vaccines use dead virus or protein fragments to trigger that response, so they can't cause infection even in someone with a weakened immune system. Live vaccines use a weakened but still-active version of the virus, which is fine for healthy immune systems but potentially dangerous when immunosuppressive medications have reduced your body's ability to contain even weakened pathogens.
For Crohn's patients, this distinction matters more than for most other conditions. Crohn's patients are frequently on combination immunosuppression, meaning a biologic like infliximab or adalimumab paired with a thiopurine like azathioprine or 6-mercaptopurine. That combination creates a deeper level of immune suppression than either drug alone, which makes the live-versus-inactivated distinction especially critical.
Which Vaccines Are Safe on Immunosuppressants
All inactivated vaccines are safe to receive while on immunosuppressive therapy. This includes the annual flu shot (the injected version, not the nasal spray), all currently available COVID-19 vaccines, Shingrix (the recombinant shingles vaccine), pneumococcal vaccines, hepatitis A and B, HPV, Tdap, and meningococcal vaccines. You may have a somewhat reduced immune response to these vaccines while on immunosuppression, but they remain safe to receive and are still strongly recommended. In fact, the Crohn's & Colitis Foundation and the American Gastroenterological Association specifically recommend staying current on all inactivated vaccines because immunosuppressed patients face higher risks from the infections these vaccines prevent.
One important nuance with the flu shot: the injectable flu vaccine is inactivated and safe on immunosuppressants. The nasal spray flu vaccine (FluMist/LAIV) is a live vaccine and should be avoided. Make sure your pharmacist knows which medications you're on when you go for your annual flu shot.
Live Vaccines to Avoid While on Treatment
Live vaccines are contraindicated for patients on immunosuppressive therapy. The concern is that the weakened live virus could cause actual infection in someone whose immune system cannot mount an adequate response. The live vaccines most relevant to Crohn's patients include MMR (measles, mumps, rubella), varicella (chickenpox), the older live shingles vaccine (Zostavax, now largely replaced by Shingrix), yellow fever, and the nasal spray flu vaccine.
If you need any of these vaccines, the timing matters. Live vaccines should be administered at least four weeks before starting immunosuppressive therapy. If you're already on treatment, you'll need to wait at least three months after stopping immunosuppression before receiving a live vaccine. That said, your GI doctor should never delay necessary Crohn's treatment just to complete a vaccination schedule. The Infectious Diseases Society of America recommends updating immunizations before starting immunosuppression when possible, but treatment comes first.
The Shingles-JAK Inhibitor Connection
Shingles deserves special attention for Crohn's patients, particularly those on JAK inhibitors like tofacitinib or upadacitinib. JAK inhibitors are associated with a significantly increased risk of herpes zoster (shingles) compared to biologics. This elevated risk is one of the most clinically relevant side effects of JAK inhibitor therapy in IBD.
The good news is that Shingrix, the current standard shingles vaccine, is a recombinant (non-live) vaccine and is safe for immunosuppressed patients. In a study of over 5,400 individuals with IBD who received two doses of the recombinant zoster vaccine, the shingles rate dropped to 1.09% compared to 2.4% in unvaccinated controls. If you're starting a JAK inhibitor, getting Shingrix at least two weeks before beginning treatment is ideal, with the second dose following eight weeks to six months later. But even if you're already on a JAK inhibitor, Shingrix remains safe and recommended.
COVID-19 Vaccines and Crohn's Medications
COVID-19 vaccines (both mRNA and protein-based) are inactivated vaccines and are safe for all Crohn's patients regardless of medication. Research from Cedars-Sinai and other institutions has confirmed that COVID-19 vaccine safety outcomes in IBD patients show no significant differences compared to the general population.
There is one caveat around effectiveness. Patients on anti-TNF biologics like infliximab, particularly when combined with thiopurines, may have a reduced initial antibody response after their first dose. However, studies show that response normalizes after the second dose. The Crohn's & Colitis Foundation recommends that immunosuppressed patients receive all recommended boosters to maintain adequate protection, and the Advisory Committee on Immunization Practices has recommended that patients on immunosuppressive therapy receive an additional primary dose of the mRNA vaccine.
The Best Time to Vaccinate Is Before You Start Treatment
The single most important takeaway is timing. Ideally, your immunization record should be reviewed and updated before you begin any immunosuppressive medication. Inactivated vaccines should be given at least two weeks, and preferably three to four weeks, before starting immunosuppression. Live vaccines need at least four weeks of lead time. Many patients and even some gastroenterologists miss this window, which means catching up later is either more complicated (for inactivated vaccines with reduced efficacy) or impossible (for live vaccines) until treatment changes.
If you're already on treatment, talk to your GI doctor about which vaccines you can and should still receive. Track your vaccination schedule alongside your medications in Aidy. Knowing exactly which immunosuppressants you're on helps you and your pharmacist make safe vaccine decisions every time.