Biologics Safety: Infection Risk, Screening, and Vaccination Guidance for Autoimmune Patients

Why Biologics Increase Your Infection Risk

Biologics are powerful drugs used to treat autoimmune diseases like rheumatoid arthritis, psoriasis, and Crohn’s disease. They work by targeting specific parts of your immune system to stop it from attacking your own body. But that same power comes with a trade-off: your body becomes less able to fight off infections. Studies show people on biologics have more than double the risk of being hospitalized for an infection compared to those on other treatments. This isn’t just a small chance-it’s a real, measurable danger that needs to be managed before you even start treatment.

The biggest culprits are TNF inhibitors like adalimumab and infliximab. These make up nearly 70% of all biologic prescriptions and carry the highest infection risk. For example, patients on adalimumab have a 1.78 times higher chance of serious infections than those not on biologics. Even newer drugs like ustekinumab aren’t risk-free, but they’re generally safer. If you have diabetes, COPD, or kidney disease, your risk jumps even higher. One study found that taking more than 10mg of prednisone daily multiplies your infection risk by 2.3 times. Age matters too-every decade over 50 adds 37% more risk.

What You Must Be Screened For Before Starting Biologics

Before you get your first biologic shot or infusion, you need three critical screenings: hepatitis B, tuberculosis, and varicella-zoster virus (chickenpox). Skipping any one of these can lead to life-threatening complications.

Hepatitis B screening isn’t optional. Even if you’ve never had symptoms, you could be carrying a hidden (occult) infection. About 4.3% of autoimmune patients have this silent form. If you’re on a TNF inhibitor and it reactivates, the chance of severe liver damage is nearly 28%. The test isn’t just one blood draw-it’s three: HBsAg, HBsAb, and HBcAb. If HBcAb is positive, you need a follow-up test for HBV DNA. Without this, you’re flying blind.

Tuberculosis screening is trickier. Most clinics use the IGRA blood test, which is 98% specific. But in low-risk areas, it can give false positives. One study found that 12.7% of patients tested positive, yet only 0.8 cases of active TB occurred per 100 patient-years. Still, guidelines require it because the consequences of missing TB are too high. If you test positive, you’ll need 9 months of antibiotics before starting your biologic.

Chickenpox history matters. If you’ve never had chickenpox or the vaccine, you’re at risk for shingles later. Shingles isn’t just a rash-it can lead to nerve pain lasting months or years. Testing for VZV IgG antibodies is simple. If your level is below 140 mIU/mL, you need the Shingrix vaccine before starting treatment.

Vaccinations: Timing Is Everything

Vaccines are your best defense-but only if given at the right time. Live vaccines like MMR and varicella must be given at least 4 weeks before your first biologic dose. Why? Because once you start the drug, your immune system won’t respond properly. You can’t get them afterward.

Inactivated vaccines like flu shots and pneumococcal vaccines can be given as close as 2 weeks before starting. But even then, you need to wait for your body to build immunity. For hepatitis B, you must confirm your antibody level is at least 10 mIU/mL after vaccination. For VZV, it’s 140 mIU/mL. If you don’t hit those numbers, you’re still vulnerable.

Here’s the hard truth: many patients get started on biologics without proper vaccination. Reddit users report that 63% have had at least one screening or vaccination skipped. One patient got Stelara without being checked for shingles vaccine history-and developed shingles four months later. That’s preventable. Always ask: “Have you checked my vaccine records?”

How Different Biologics Compare in Infection Risk

Not all biologics are created equal. TNF inhibitors are the most risky, but newer classes have different profiles.

• TNF inhibitors (adalimumab, infliximab): Highest overall infection risk. Avoid if you have chronic hepatitis B-reactivation risk is 27.6% without treatment.
• IL-12/23 inhibitors (ustekinumab): Much lower infection risk. Safer for hepatitis B carriers. Only 1.2% reactivation rate.
• IL-17 inhibitors (secukinumab): Lower respiratory infections but higher risk of candidiasis (yeast infections), especially in the mouth or genitals.
• Certolizumab pegol: Unique because it lacks an Fc region. Shows 18% lower respiratory infection rates than other TNF drugs.
• JAK inhibitors (tofacitinib): Not technically biologics, but often grouped with them. Carry a 1.33x higher risk of shingles than biologics.

If you’ve had multiple infections on one drug, switching classes might help. For example, switching from adalimumab to ustekinumab can cut your infection risk significantly. Talk to your doctor about your personal risk history-not just the drug label.

What Happens If You Skip Screening or Vaccinations

Skipping steps doesn’t mean you’ll definitely get sick. But the odds stack up fast. One study of over 2,000 patients found that those who received full pre-treatment education-including the CDC’s 12-point checklist-had zero serious infections. Those who didn’t? 43% had at least one. That’s a 78% reduction in risk just from following protocol.

Real-world data shows clinics often miss key steps. HBV core antibody testing is skipped in 41% of cases. VZV serology? 37%. Even when tests are done, results aren’t always followed up. One CMS audit found that nearly 24% of practices didn’t keep screening records for the required 10 years. That’s not just bad practice-it’s a legal and safety failure.

And it’s not just about the drugs. Environmental factors matter too. Norovirus survives 30 days on surfaces. Influenza lasts less than a day. If you’re on a biologic, you’re more vulnerable to anything that’s airborne or touched by others. Handwashing, avoiding sick people, and staying up to date on flu shots aren’t suggestions-they’re survival tactics.

What’s Changing in 2025 and Beyond

Regulations are tightening. In February 2025, the FDA proposed new rules requiring drug makers to prove their biologics don’t cause more infections than current options before they can expand their labels. This comes after Xeljanz was linked to higher infection rates than TNF inhibitors.

AI tools are now being used to predict risk. The Cerner Biologics Safety Algorithm analyzes 87 clinical factors-like age, kidney function, diabetes control, and past infections-to give you a personalized risk score. It’s not perfect, but it’s better than guessing.

Insurance is catching up too. Starting in 2026, Medicare will tie 15% of biologic payments to whether clinics followed infection prevention protocols. That means doctors will have more incentive to do screenings right. But until then, you need to be your own advocate. Don’t assume your doctor knows all the steps. Bring the CDC checklist. Ask for your HBV and VZV results. Demand proof of vaccination before you start.

What You Can Do Today

Don’t wait for your next appointment. Take action now:

1. Call your doctor’s office and ask: “What infection screenings have been done for me?”
2. Request your HBV test results: HBsAg, HBsAb, and HBcAb. If any are missing, get them done.
3. Check your VZV IgG level. If you’re unsure if you had chickenpox or the vaccine, assume you’re not protected.
4. Ask if you’ve had pneumococcal and flu vaccines in the last year. If not, schedule them now.
5. Bring this checklist to your next visit. Write down the answers.

Biologics can change your life for the better. But they’re not magic. They require discipline, preparation, and vigilance. The difference between getting sick and staying healthy often comes down to a few blood tests and two vaccine shots-done at the right time. Don’t let a simple oversight cost you your health.